[ { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/e7nwa-xq689", "eprint_status": "archive", "datestamp": "2023-12-20 17:32:51", "lastmod": "2023-12-20 17:32:51", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Catherall-David-S", "name": { "family": "Catherall", "given": "David S." }, "orcid": "0000-0002-3540-2419" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Hot-hole transport and noise phenomena in silicon at cryogenic temperatures from first principles", "ispublished": "pub", "full_text_status": "public", "note": "
\u00a9 2023 American Physical Society.
\n\nThis work was supported by the National Science Foundation under Award No. 1911926.
", "abstract": "The transport properties of hot holes in silicon at cryogenic temperatures exhibit several anomalous features, including the emergence of two distinct saturated drift velocity regimes and a nonmonotonic trend of the current noise versus electric field at microwave frequencies. Despite prior investigations, these features lack generally accepted explanations. Here, we examine the microscopic origin of these phenomena by extending a recently developed ab initio theory of high-field transport and noise in semiconductors. We find that the drift velocity anomaly may be attributed to scattering dominated by acoustic phonon emission, leading to an additional regime of drift velocity saturation at temperatures \u223c40 K for which the acoustic phonon occupation is negligible; while the nonmonotonic trend in the current noise arises due to the decrease in momentum relaxation time with electric field. The former conclusion is consistent with the findings of prior work, but the latter distinctly differs from previous explanations. This work highlights the use of high-field transport and noise phenomena as sensitive probes of microscopic charge transport phenomena in semiconductors.
", "date": "2023-12-15", "date_type": "published", "publication": "Physical Review B", "volume": "108", "number": "23", "publisher": "American Physical Society", "pagerange": "235207", "issn": "2469-9950", "official_url": "https://authors.library.caltech.edu/records/e7nwa-xq689", "funders": { "items": [ { "grant_number": "ECCS-1911926" } ] }, "doi": "10.1103/physrevb.108.235207", "primary_object": { "basename": "PhysRevB.108.235207.pdf", "url": "https://authors.library.caltech.edu/records/e7nwa-xq689/files/PhysRevB.108.235207.pdf" }, "resource_type": "article", "pub_year": "2023", "author_list": "Catherall, David S. and Minnich, Austin J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/shr01-xsn37", "eprint_status": "archive", "datestamp": "2023-10-18 18:16:31", "lastmod": "2023-10-18 18:16:31", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hossain-Azmain-A", "name": { "family": "Hossain", "given": "Azmain A." }, "orcid": "0000-0002-4980-1437" }, { "id": "Wang-Haozhe", "name": { "family": "Wang", "given": "Haozhe" }, "orcid": "0000-0001-5123-1077" }, { "id": "Catherall-David-S", "name": { "family": "Catherall", "given": "David S." }, "orcid": "0000-0002-3540-2419" }, { "id": "Leung-Martin", "name": { "family": "Leung", "given": "Martin" }, "orcid": "0009-0001-5209-2424" }, { "id": "Knoops-Harm-C-M", "name": { "family": "Knoops", "given": "Harm C. M." }, "orcid": "0000-0003-2284-4477" }, { "id": "Renzas-James-R", "name": { "family": "Renzas", "given": "James R." }, "orcid": "0000-0001-9117-7546" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Isotropic plasma-thermal atomic layer etching of superconducting titanium nitride films using sequential exposures of molecular oxygen and SF\u2086/H\u2082 plasma", "ispublished": "pub", "full_text_status": "restricted", "keywords": "Surfaces, Coatings and Films; Surfaces and Interfaces; Condensed Matter Physics", "note": "\u00a9 2023 Published under an exclusive license by the AVS.
\n\nThis work was supported by NSF under Award No. 2234390. The authors thank Nicholas Chittock (Eindhoven University of Technology) for useful discussions and Phillipe Pearson (California Institute of Technology) for assistance with the wirebonder. We gratefully acknowledge the critical support and infrastructure provided for this work by The Kavli Nanoscience Institute and the Molecular Materials Research Center of the Beckman Institute at the California Institute of Technology.
\n\nAzmain A. Hossain: Conceptualization (equal); Data curation (lead); Formal analysis (lead); Investigation (equal); Methodology (equal); Validation (equal); Visualization (equal); Writing \u2013 original draft (lead); Writing \u2013 review & editing (lead). Haozhe Wang: Data curation (supporting); Formal analysis (supporting); Investigation (supporting). David S. Catherall: Data curation (supporting); Formal analysis (supporting); Investigation (supporting); Methodology (equal); Writing \u2013 review & editing (supporting). Martin Leung: Data curation (supporting); Formal analysis (supporting). Harm C. M. Knoops: Conceptualization (equal); Methodology (equal); Writing \u2013 review & editing (equal). James R. Renzas: Conceptualization (equal); Methodology (equal); Writing \u2013 review & editing (equal). Austin J. Minnich: Conceptualization (equal); Formal analysis (equal); Funding acquisition (lead); Investigation (lead); Methodology (equal); Project administration (lead); Resources (lead); Supervision (lead); Validation (lead); Visualization (lead); Writing \u2013 original draft (lead); Writing \u2013 review & editing (lead).
\n\nThe data that support the findings of this study are available from the corresponding author upon reasonable request.
\n\nThe authors have no conflicts to disclose.
", "abstract": "Microwave loss in superconducting TiN films is attributed to two-level systems in various interfaces arising in part from oxidation and microfabrication-induced damage. Atomic layer etching (ALE) is an emerging subtractive fabrication method which is capable of etching with angstrom-scale etch depth control and potentially less damage. However, while ALE processes for TiN have been reported, they either employ HF vapor, incurring practical complications, or the etch rate lacks the desired control. Furthermore, the superconducting characteristics of the etched films have not been characterized. Here, we report an isotropic plasma-thermal TiN ALE process consisting of sequential exposures to molecular oxygen and an SF\u2086/H\u2082 plasma. For certain ratios of SF\u2086:H\u2082 flow rates, we observe selective etching of TiO\u2082 over TiN, enabling self-limiting etching within a cycle. Etch rates were measured to vary from 1.1\u2009\u00c5/cycle at 150\u00b0C to 3.2\u2009\u00c5/cycle at 350\u00b0C using ex situ ellipsometry. We demonstrate that the superconducting critical temperature of the etched film does not decrease beyond that expected from the decrease in film thickness, highlighting the low-damage nature of the process. These findings have relevance for applications of TiN in microwave kinetic inductance detectors and superconducting qubits.
", "date": "2023-12", "date_type": "published", "publication": "Journal of Vacuum Science & Technology A", "volume": "41", "number": "6", "publisher": "American Vacuum Society", "pagerange": "062601", "issn": "0734-2101", "official_url": "https://authors.library.caltech.edu/records/shr01-xsn37", "funders": { "items": [ { "grant_number": "CMMI-2234390" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1116/6.0002965", "primary_object": { "basename": "062601_1_6.0002965.pdf", "url": "https://authors.library.caltech.edu/records/shr01-xsn37/files/062601_1_6.0002965.pdf" }, "resource_type": "article", "pub_year": "2023", "author_list": "Hossain, Azmain A.; Wang, Haozhe; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/wm5ga-hxq22", "eprint_status": "archive", "datestamp": "2023-10-18 16:14:12", "lastmod": "2023-10-18 16:14:12", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Esho-Iretomiwa", "name": { "family": "Esho", "given": "Iretomiwa" }, "orcid": "0000-0002-3746-6571" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Charge transport in BAs and the role of two-phonon scattering", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2023 American Physical Society.
\n\nI.E. was supported by a National Science Foundation Graduate Research Fellowship under Grant No. DGE-1745301. A.J.M. was supported by AFOSR under Grant No. FA9550-19-1-0321. The authors thank Benjamin Hatanp\u00e4\u00e4 for useful discussions and providing data on intervalley scattering in Si.
", "abstract": "The semiconductor BAs has drawn significant interest due to experimental reports of simultaneous high thermal conductivity and ambipolar charge mobility. The ab initio prediction of high electron and hole mobility assumed the dominance of charge carrier scattering by one phonon. Recently, higher-order electron-phonon scattering processes in polar and nonpolar semiconductors have been reported to have a non-negligible impact on charge transport properties, suggesting they may play a role in BAs as well. Here, we report an ab initio study of two-phonon electron and hole scattering processes in BAs. We find that inclusion of these higher-order processes reduces the computed room-temperature electron and hole mobility in BAs by around 40% from the one-phonon value, resulting in an underestimate of experimental values by a similar percentage. We suggest an experimental approach to test these predictions using luminescence spectroscopy that is applicable to the defective samples which are presently available.
", "date": "2023-10-15", "date_type": "published", "publication": "Physical Review B", "volume": "108", "number": "16", "publisher": "American Physical Society", "pagerange": "165202", "issn": "2469-9950", "official_url": "https://authors.library.caltech.edu/records/wm5ga-hxq22", "funders": { "items": [ { "grant_number": "DGE-1745301" }, { "grant_number": "FA9550-19-1-0321" } ] }, "doi": "10.1103/physrevb.108.165202", "primary_object": { "basename": "PhysRevB.108.165202.pdf", "url": "https://authors.library.caltech.edu/records/wm5ga-hxq22/files/PhysRevB.108.165202.pdf" }, "resource_type": "article", "pub_year": "2023", "author_list": "Esho, Iretomiwa and Minnich, Austin J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/yk53c-fs627", "eprint_id": 121908, "eprint_status": "archive", "datestamp": "2023-08-22 21:07:20", "lastmod": "2023-10-20 16:47:28", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Koh-Jin-Ming", "name": { "family": "Koh", "given": "Jin Ming" }, "orcid": "0000-0002-6130-5591" }, { "id": "Sun-Shi-Ning", "name": { "family": "Sun", "given": "Shi-Ning" }, "orcid": "0000-0002-5984-780X" }, { "id": "Motta-Mario", "name": { "family": "Motta", "given": "Mario" }, "orcid": "0000-0003-1647-9864" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Measurement-induced entanglement phase transition on a superconducting quantum processor with mid-circuit readout", "ispublished": "pub", "full_text_status": "public", "keywords": "General Physics and Astronomy", "note": "\u00a9 The Author(s), under exclusive licence to Springer Nature Limited 2023. \n\nS.S. and A.J.M. were supported by the US Department of Energy under award no. DE-SC0019374. M.M. acknowledges J. Burks, D. McClure, S. Sheldon and M. Stypulkoski for help with access to, and use of, IBM Quantum devices. M.M. also acknowledges helpful discussions with L. Govia, E. Chen, and A. Kandala. The authors acknowledge the use of IBM Quantum services for this work. \n\nContributions. J.M.K., S.-N.S. and A.J.M. conceived and initiated the project. A.J.M. supervised the project. J.M.K. developed the quantum simulation codebase and ran experiments on emulators and quantum hardware. M.M. contributed to the codebase and ran experiments on quantum hardware. All authors contributed to the discussion of results and writing of the paper. \n\nData availability. Data that support the findings of this study are publicly available via the Open Science Framework at https://osf.io/wkx49/. \n\nCode availability. Code used in this study is publicly available via the Open Science Framework at https://osf.io/wkx49/. \n\nThe authors declare no competing interests.\n\nSupplemental Material - 41567_2023_2076_MOESM1_ESM.pdf
", "abstract": "Quantum many-body systems subjected to unitary evolution with the addition of interspersed measurements exhibit a variety of dynamical phases that do not occur under pure unitary evolution. However, these systems remain challenging to investigate on near-term quantum hardware owing to the need for numerous ancilla qubits or repeated high-fidelity mid-circuit measurements, a capability that has only recently become available. Here we report the realization of a measurement-induced entanglement phase transition with a hybrid random circuit on up to 14 superconducting qubits with mid-circuit readout capability. We directly observe extensive and sub-extensive scaling of entanglement entropy in the volume- and area-law phases, respectively, by varying the rate of the measurements. We also demonstrate phenomenological critical behaviour by performing a data collapse of the measured entanglement entropy. Our work establishes the use of mid-circuit measurement as a powerful resource for quantum simulation on near-term quantum computers.", "date": "2023-06-16", "date_type": "published", "publication": "Nature Physics", "publisher": "Nature Publishing Group", "id_number": "CaltechAUTHORS:20230615-216273000.1", "issn": "1745-2473", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230615-216273000.1", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0019374" } ] }, "doi": "10.1038/s41567-023-02076-6", "primary_object": { "basename": "41567_2023_2076_MOESM1_ESM.pdf", "url": "https://authors.library.caltech.edu/records/yk53c-fs627/files/41567_2023_2076_MOESM1_ESM.pdf" }, "resource_type": "article", "pub_year": "2023", "author_list": "Koh, Jin Ming; Sun, Shi-Ning; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/jes2z-m5p24", "eprint_id": 121658, "eprint_status": "archive", "datestamp": "2023-08-20 16:52:24", "lastmod": "2023-10-20 15:42:04", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sun-Jiace", "name": { "family": "Sun", "given": "Jiace" }, "orcid": "0000-0002-0566-2084" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Transport and noise of hot electrons in GaAs using a semianalytical model of two-phonon polar optical phonon scattering", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2023 American Physical Society. \n\nThis work was supported by AFOSR under Grant No. FA9550-19-1-0321. The authors thank P. Cheng, B. Hatanp\u00e4\u00e4, D. Catherall, S-N. Sun, and T. Esho for helpful discussions.\n\nPublished - PhysRevB.107.205201.pdf
", "abstract": "Recent ab initio studies of electron transport in GaAs have reported that electron-phonon (e-ph) interactions beyond the lowest order play a fundamental role in charge transport and noise phenomena. Inclusion of the next-leading-order process in which an electron scatters with two phonons was found to yield good agreement for the high-field drift velocity, but the characteristic nonmonotonic trend of the power spectral density of current fluctuations (PSD) with electric field was not predicted. The high computational cost of the ab initio approach necessitated various approximations to the two-phonon scattering term, which were suggested as possible origins of the discrepancy. Here we report a semianalytical transport model of two-phonon electron scattering via the Fr\u00f6hlich mechanism, allowing a number of the approximations in the ab initio treatment to be lifted while retaining the accuracy to within a few percent. We compare the calculated and experimental transport and noise properties as well as scattering rates measured by photoluminescence experiments. We find quantitative agreement within 15% for the drift velocity and 25% for the \u0393 valley scattering rates, and agreement with the \u0393\u2212L intervalley scattering rates within a factor of two. Considering these results and prior studies of current noise in GaAs, we conclude that the most probable origin of the nonmonotonic PSD trend versus electric field is the formation of space-charge domains rather than intervalley scattering as has been assumed.", "date": "2023-05-15", "date_type": "published", "publication": "Physical Review B", "volume": "107", "number": "20", "publisher": "American Physical Society", "pagerange": "Art. No. 205201", "id_number": "CaltechAUTHORS:20230601-102106000.1", "issn": "2469-9950", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230601-102106000.1", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-19-1-0321" } ] }, "doi": "10.1103/physrevb.107.205201", "primary_object": { "basename": "PhysRevB.107.205201.pdf", "url": "https://authors.library.caltech.edu/records/jes2z-m5p24/files/PhysRevB.107.205201.pdf" }, "resource_type": "article", "pub_year": "2023", "author_list": "Sun, Jiace and Minnich, Austin J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/10vc6-8pt19", "eprint_id": 121519, "eprint_status": "archive", "datestamp": "2023-08-22 20:48:33", "lastmod": "2023-10-20 15:31:06", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Wang-Haozhe", "name": { "family": "Wang", "given": "Haozhe" }, "orcid": "0000-0001-5123-1077" }, { "id": "Hossain-Azmain", "name": { "family": "Hossain", "given": "Azmain" }, "orcid": "0000-0002-4980-1437" }, { "id": "Catherall-David-S", "name": { "family": "Catherall", "given": "David" }, "orcid": "0000-0002-3540-2419" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Isotropic plasma-thermal atomic layer etching of aluminum nitride using SF\u2086 plasma and Al(CH\u2083)\u2083", "ispublished": "pub", "full_text_status": "restricted", "keywords": "Surfaces, Coatings and Films; Surfaces and Interfaces; Condensed Matter Physics", "note": "This work was supported by the Kavli Foundation and by the AFOSR under Grant No. FA9550-19-1-0321. The authors thank Nicholas Chittock, Guy DeRose, Harm Knoops, Kelly McKenzie, and Russ Renzas for useful discussions. We gratefully acknowledge the critical support and infrastructure provided for this work by The Kavli Nanoscience Institute and the Molecular Materials Research Center of the Beckman Institute at the California Institute of Technology.\n\nAuthor Contributions: Haozhe Wang: Conceptualization (equal); Data curation (equal); Formal analysis (equal); Investigation (equal); Methodology (equal); Supervision (equal); Validation (equal); Writing \u2013 original draft (equal); Writing \u2013 review & editing (equal). Azmain Hossain: Data curation (supporting); Formal analysis (supporting); Investigation (supporting). David Catherall: Data curation (supporting); Formal analysis (supporting); Investigation (supporting); Methodology (supporting). Austin J. Minnich: Conceptualization (equal); Formal analysis (equal); Funding acquisition (equal); Investigation (equal); Methodology (equal); Project administration (equal); Resources (equal); Supervision (equal); Validation (equal); Visualization (equal); Writing \u2013 original draft (equal); Writing \u2013 review & editing (equal). \n\nData Availability: The data that support the findings of this study are available from the corresponding author upon reasonable request. \n\nThe authors have no conflicts to disclose.", "abstract": "We report the isotropic plasma atomic layer etching (ALE) of aluminum nitride using sequential exposures of SF\u2086 plasma and trimethylaluminum [Al(CH\u2083)\u2083]. ALE was observed at temperatures greater than 200\u2218C, with a maximum etch rate of 1.9\u2009\u00c5/cycle observed at 300\u2218C as measured using ex situ ellipsometry. After ALE, the etched surface was found to contain a lower concentration of oxygen compared to the original surface and exhibited a \u223c35% decrease in surface roughness. These findings have relevance for applications of AlN in nonlinear photonics and wide bandgap semiconductor devices.", "date": "2023-05", "date_type": "published", "publication": "Journal of Vacuum Science and Technology A", "volume": "41", "number": "3", "publisher": "American Vacuum Society", "pagerange": "Art. No. 032606", "id_number": "CaltechAUTHORS:20230525-771644200.4", "issn": "0734-2101", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230525-771644200.4", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-19-1-0321" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1116/6.0002476", "resource_type": "article", "pub_year": "2023", "author_list": "Wang, Haozhe; Hossain, Azmain; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/60w1q-aj959", "eprint_id": 121180, "eprint_status": "archive", "datestamp": "2023-08-20 07:15:16", "lastmod": "2023-10-20 15:20:46", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Koh-Jin-Ming", "name": { "family": "Koh", "given": "Jin Ming" }, "orcid": "0000-0002-6130-5591" }, { "id": "Sun-Shi-Ning", "name": { "family": "Sun", "given": "Shi-Ning" }, "orcid": "0000-0002-5984-780X" }, { "id": "Motta-Mario", "name": { "family": "Motta", "given": "Mario" }, "orcid": "0000-0003-1647-9864" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Experimental Realization of a Measurement-Induced Entanglement Phase Transition on a Superconducting Quantum Processor", "ispublished": "unpub", "full_text_status": "public", "note": "S.S. and A.J.M. were supported by the U.S. Department of Energy under Award No. DE-SC0019374. M. M. acknowledges Jody Burks, Douglas McClure, Sarah Sheldon, and Matthew Stypulkoski for help with access to, and use of, IBM Quantum devices. The authors acknowledge the use of IBM Quantum services for this work. \n\nDATA AVAILABILITY. The data that support the findings of this study are available from the corresponding author upon reasonable request. \n\nCODE AVAILABILITY. The code used in this study is available from the corresponding author upon reasonable request. \n\nThe authors declare no competing interests.\n\nSubmitted - 2203.04338.pdf
", "abstract": "Ergodic quantum many-body systems undergoing unitary dynamics evolve towards increasingly entangled states characterized by an extensive scaling of entanglement entropy with system volume. At the other extreme, quantum systems repeatedly measured may be stabilized in a measurement eigenstate, a phenomenon known as the quantum Zeno effect. Recently, the intermediate regime in which unitary evolution is interspersed with quantum measurements has become of interest. Numerical studies have reported the existence of distinct phases characterized by volume- and area-law entanglement entropy scaling for infrequent and frequent measurement rates, respectively, separated by a critical measurement rate. The experimental investigation of these dynamic quantum phases of matter on near-term quantum hardware is challenging due to the need for repeated high-fidelity mid-circuit measurements and fine control over the evolving unitaries. Here, we report the realization of a measurement-induced entanglement transition on superconducting quantum processors with mid-circuit readout capability. We directly observe extensive and sub-extensive scaling of entanglement entropy in the volume- and area-law phases, respectively, by varying the rate of projective measurements. We further demonstrate phenomenological critical behavior of the transition by performing a data collapse for different system sizes. Our work paves the way for the use of mid-circuit measurement as an effective resource for quantum simulation on near-term quantum computers, for instance by facilitating the study of dynamic and long-range entangled quantum phases.", "date": "2023-04-26", "date_type": "published", "publisher": "arXiv", "id_number": "CaltechAUTHORS:20230426-214259756", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230426-214259756", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0019374" } ] }, "primary_object": { "basename": "2203.04338.pdf", "url": "https://authors.library.caltech.edu/records/60w1q-aj959/files/2203.04338.pdf" }, "resource_type": "monograph", "pub_year": "2023", "author_list": "Koh, Jin Ming; Sun, Shi-Ning; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/spagn-em992", "eprint_id": 121107, "eprint_status": "archive", "datestamp": "2023-08-20 16:39:09", "lastmod": "2023-10-23 15:39:28", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Tan-Adrian-T-K", "name": { "family": "Tan", "given": "Adrian T. K." }, "orcid": "0000-0002-6660-0397" }, { "id": "Sun-Shi-Ning", "name": { "family": "Sun", "given": "Shi-Ning" }, "orcid": "0000-0002-5984-780X" }, { "id": "Tazhigulov-Ruslan-N", "name": { "family": "Tazhigulov", "given": "Ruslan N." }, "orcid": "0000-0002-0679-3078" }, { "id": "Chan-Garnet-K-L", "name": { "family": "Chan", "given": "Garnet Kin-Lic" }, "orcid": "0000-0001-8009-6038" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Realizing symmetry-protected topological phases in a spin-1/2 chain with next-nearest-neighbor hopping on superconducting qubits", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2023 American Physical Society. \n\nThe authors thank M. Wojciech, N. C. Rubin, Z. Jiang, and R. Babbush for helpful discussions. A.T.K.T., S.-N.S., A.J.M., and G.K.-L.C. were supported by the U.S. NSF under Award No. 1839204. R.N.T. was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Award No. DE-SC0019374.\n\nPublished - PhysRevA.107.032614.pdf
", "abstract": "Quantum simulation on near-term quantum hardware is a topic of intense interest. The preparation of novel quantum states of matter provides a quantitative assessment of the capabilities of near-term digital quantum computers to implement circuits with structure of relevance to quantum simulation. Here, we conduct a benchmark study by realizing symmetry-protected topological (SPT) phases of a spin-1/2 Hamiltonian with next-nearest-neighbor hopping on up to 11 qubits on a programmable superconducting quantum processor using adiabatic state preparation. Using recompilation techniques to reduce the gate count to around 50 two-qubit gates, we observe clear signatures of the two distinct SPT phases, such as excitations localized to specific edges and finite string-order parameters. We identify a parasitic phase associated with the two-qubit gate as the dominant imperfection that limits the depth of the circuits, indicating a research topic of interest for future hardware development.", "date": "2023-03", "date_type": "published", "publication": "Physical Review A", "volume": "107", "number": "3", "publisher": "American Physical Society", "pagerange": "Art. No. 032614", "id_number": "CaltechAUTHORS:20230420-574389200.10", "issn": "2469-9926", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230420-574389200.10", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CCF-1839204" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0019374" } ] }, "doi": "10.1103/physreva.107.032614", "primary_object": { "basename": "PhysRevA.107.032614.pdf", "url": "https://authors.library.caltech.edu/records/spagn-em992/files/PhysRevA.107.032614.pdf" }, "resource_type": "article", "pub_year": "2023", "author_list": "Tan, Adrian T. K.; Sun, Shi-Ning; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/2vc9z-3nk08", "eprint_id": 119006, "eprint_status": "archive", "datestamp": "2023-08-20 09:01:07", "lastmod": "2023-10-23 15:13:20", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Catherall-David-S", "name": { "family": "Catherall", "given": "David S." }, "orcid": "0000-0002-3540-2419" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "High-field charge transport and noise in p-Si from first principles", "ispublished": "pub", "full_text_status": "public", "note": "This work was supported by the National Science Foundation under Award No. 1911926. We thank A. Choi, B. Hatanp\u00e4\u00e4, P. Cheng, S-N. Sun, and J. Sun for code development and discussions.", "abstract": "The parameter-free computation of charge transport properties of semiconductors is now routine owing to advances in the ab initio description of the electron-phonon interaction. Many studies focus on the low-field regime in which the carrier temperature equals the lattice temperature and the current power spectral density (PSD) is proportional to the mobility. The calculation of high-field transport and noise properties offers a stricter test of the theory as these relations no longer hold, yet few such calculations have been reported. Here, we compute the high-field mobility and PSD of hot holes in silicon from first principles at temperatures of 77 and 300 K and electric fields up to 20 kV cm\u207b\u00b9 along various crystallographic axes. We find that the calculations quantitatively reproduce experimental trends including the anisotropy and electric-field dependence of hole mobility and PSD. The experimentally observed rapid variation of energy relaxation time with electric field at cryogenic temperatures is also correctly predicted. However, as in low-field studies, absolute quantitative agreement is, in general, lacking, a discrepancy that has been attributed to inaccuracies in the calculated valence-band structure. Our paper highlights the use of high-field transport and noise properties as a rigorous test of the theory of electron-phonon interactions in semiconductors.", "date": "2023-01-15", "date_type": "published", "publication": "Physical Review B", "volume": "107", "number": "3", "publisher": "American Physical Society", "pagerange": "Art. No. 035201", "id_number": "CaltechAUTHORS:20230203-893210800.7", "issn": "2469-9950", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230203-893210800.7", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "ECCS-1911926" } ] }, "doi": "10.1103/physrevb.107.035201", "resource_type": "article", "pub_year": "2023", "author_list": "Catherall, David S. and Minnich, Austin J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/eqd63-0sk32", "eprint_id": 120043, "eprint_status": "archive", "datestamp": "2023-08-20 09:01:37", "lastmod": "2023-10-23 15:13:25", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hatanp\u00e4\u00e4-Benjamin", "name": { "family": "Hatanp\u00e4\u00e4", "given": "Benjamin" }, "orcid": "0000-0002-8441-0183" }, { "id": "Choi-Alexander-Y", "name": { "family": "Choi", "given": "Alexander Y." }, "orcid": "0000-0003-2006-168X" }, { "id": "Cheng-Peishi-S", "name": { "family": "Cheng", "given": "Peishi S." }, "orcid": "0000-0002-3513-9972" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Two-phonon scattering in nonpolar semiconductors: A first-principles study of warm electron transport in Si", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2023 American Physical Society. \n\nB.H. was supported by a NASA Space Technology Graduate Research Opportunity under Grant No. 80NSSC21K1280. A.Y.C., P.S.C., and A.J.M. were supported by AFOSR under Grant No. FA9550-19-1-0321. The authors thank J. Sun, S. Sun, D. Catherall, and T. Esho for helpful discussions.\n\nPublished - PhysRevB.107.L041110.pdf
Supplemental Material - supplemental.pdf
", "abstract": "The ab initio theory of charge transport in semiconductors typically employs the lowest-order perturbation theory in which electrons interact with one phonon (1ph). This theory is accepted to be adequate to explain the low-field mobility of nonpolar semiconductors but has not been tested extensively beyond the low-field regime. Here, we report first-principles calculations of the electric field dependence of the electron mobility of Si as described by the warm electron coefficient \u03b2. Although the 1ph theory overestimates the low-field mobility by only around 20%, it overestimates \u03b2 by over a factor of two over a range of temperatures and crystallographic axes. We show that the discrepancy in \u03b2 is reconciled by the inclusion of on-shell iterated two-phonon (2ph) scattering processes, indicating that scattering from higher-order electron-phonon interactions is non-negligible even in nonpolar semiconductors. Further, a \u223c20% underestimate of the low-field mobility with 2ph scattering suggests that nontrivial cancellations may occur in the perturbative expansion of the electron-phonon interaction.", "date": "2023-01-15", "date_type": "published", "publication": "Physical Review B", "volume": "107", "number": "4", "publisher": "American Physical Society", "pagerange": "Art. No. L041110", "id_number": "CaltechAUTHORS:20230314-846094500.76", "issn": "2469-9950", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230314-846094500.76", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA Space Technology Research Fellowship", "grant_number": "80NSSC21K1280" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-19-1-0321" } ] }, "doi": "10.1103/physrevb.107.l041110", "primary_object": { "basename": "PhysRevB.107.L041110.pdf", "url": "https://authors.library.caltech.edu/records/eqd63-0sk32/files/PhysRevB.107.L041110.pdf" }, "related_objects": [ { "basename": "supplemental.pdf", "url": "https://authors.library.caltech.edu/records/eqd63-0sk32/files/supplemental.pdf" } ], "resource_type": "article", "pub_year": "2023", "author_list": "Hatanp\u00e4\u00e4, Benjamin; Choi, Alexander Y.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/m4h49-2t871", "eprint_id": 119005, "eprint_status": "archive", "datestamp": "2023-08-20 08:53:31", "lastmod": "2023-10-23 15:30:06", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Cheng-Peishi-S", "name": { "family": "Cheng", "given": "Peishi S." }, "orcid": "0000-0002-3513-9972" }, { "id": "Sun-Jiace", "name": { "family": "Sun", "given": "Jiace" }, "orcid": "0000-0002-0566-2084" }, { "id": "Sun-Shi-Ning", "name": { "family": "Sun", "given": "Shi-Ning" }, "orcid": "0000-0002-5984-780X" }, { "id": "Choi-Alexander-Y", "name": { "family": "Choi", "given": "Alexander Y." }, "orcid": "0000-0003-2006-168X" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "High-field transport and hot-electron noise in GaAs from first-principles calculations: Role of two-phonon scattering", "ispublished": "pub", "full_text_status": "public", "note": "This work was supported by AFOSR under Grant No. FA9550-19-1-0321. The authors thank B. Hatanp\u00e4\u00e4, D. Catherall, and T. Esho for helpful discussions.", "abstract": "High-field charge transport in semiconductors is of fundamental interest and practical importance. While the ab initio treatment of low-field transport is well developed, the treatment of high-field transport is much less so, particularly for multiphonon processes that are reported to be relevant in GaAs. Here, we report a calculation of the high-field transport properties and current power spectral density (PSD) of hot electrons in GaAs from first principles including on-shell two-phonon (2ph) scattering. The on-shell 2ph scattering rates are found to qualitatively alter the high-field distribution function by increasing both the momentum and energy relaxation rates as well as contributing markedly to intervalley scattering. This finding reconciles a long-standing discrepancy regarding the strength of intervalley scattering in GaAs as inferred from transport and optical studies. The characteristic nonmonotonic trend of PSD with electric field is not predicted at this level of theory. Our work shows how ab initio calculations of high-field transport and noise may be used as a stringent test of the electron-phonon interaction in semiconductors.", "date": "2022-12-15", "date_type": "published", "publication": "Physical Review B", "volume": "106", "number": "24", "publisher": "American Physical Society", "pagerange": "Art. No. 245201", "id_number": "CaltechAUTHORS:20230203-893210800.6", "issn": "2469-9950", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230203-893210800.6", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-19-1-0321" } ] }, "doi": "10.1103/physrevb.106.245201", "resource_type": "article", "pub_year": "2022", "author_list": "Cheng, Peishi S.; Sun, Jiace; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/nnrw2-ppf14", "eprint_id": 118206, "eprint_status": "archive", "datestamp": "2023-08-22 18:05:30", "lastmod": "2023-10-23 20:12:58", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Tazhigulov-Ruslan-N", "name": { "family": "Tazhigulov", "given": "Ruslan N." }, "orcid": "0000-0002-0679-3078" }, { "id": "Sun-Shi-Ning", "name": { "family": "Sun", "given": "Shi-Ning" }, "orcid": "0000-0002-5984-780X" }, { "id": "Haghshenas-Reza", "name": { "family": "Haghshenas", "given": "Reza" }, "orcid": "0000-0002-5593-8915" }, { "id": "Zhai-Huanchen", "name": { "family": "Zhai", "given": "Huanchen" }, "orcid": "0000-0003-0086-0388" }, { "id": "Tan-Adrian-T-K", "name": { "family": "Tan", "given": "Adrian T. K." }, "orcid": "0000-0002-6660-0397" }, { "id": "Rubin-Nicholas-C", "name": { "family": "Rubin", "given": "Nicholas C." }, "orcid": "0000-0003-3963-1830" }, { "id": "Babbush-Ryan", "name": { "family": "Babbush", "given": "Ryan" }, "orcid": "0000-0001-6979-9533" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" }, { "id": "Chan-Garnet-K-L", "name": { "family": "Chan", "given": "Garnet Kin-Lic" }, "orcid": "0000-0001-8009-6038" } ] }, "title": "Simulating Models of Challenging Correlated Molecules and Materials on the Sycamore Quantum Processor", "ispublished": "pub", "full_text_status": "public", "keywords": "General Earth and Planetary Sciences; General Environmental Science", "note": "R.N.T., R.H., and G.K.-L.C. were supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Award No. DE-SC0019374. S.-N.S., A.T.K.T., and A.J.M. were supported by the U.S. National Science Foundation (NSF) under Award No. 1839204. Additional support for R.N.T. was provided by the Dreyfus Foundation. The quantum hardware used in this work was developed by the Google Quantum AI team. Data were collected via cloud access through Google's Quantum Computing Service.\n\nR.N.T., R.H., and G.K.-L.C. conceptualized the project. R.N.T. and S.-N.S. designed and implemented the circuits with help from R.H., while R.N.T. executed the simulations and analyzed the results. R.N.T. and G.K.-L.C. wrote the paper. All authors discussed the results and contributed to the development of the manuscript.\n\nG.K.-L.C. is a part owner of QSimulate, Inc.", "abstract": "Simulating complex molecules and materials is an anticipated application of quantum devices. With the emergence of hardware designed to target strong quantum advantage in artificial tasks, we examine how the same hardware behaves in modeling physical problems of correlated electronic structure. We simulate static and dynamical electronic structure on a superconducting quantum processor derived from Google's Sycamore architecture for two representative correlated electron problems: the nitrogenase iron-sulfur molecular clusters and \u03b1-ruthenium trichloride, a proximate spin-liquid material. To do so, we simplify the electronic structure into low-energy spin models that fit on the device. With extensive error mitigation and assistance from classical recompilation and simulated data, we achieve quantitatively meaningful results deploying about one fifth of the gate resources used in artificial quantum advantage experiments on a similar architecture. This increases to over half of the gate resources when choosing a model that suits the hardware. Our work serves to convert artificial measures of quantum advantage into a physically relevant setting.", "date": "2022-11", "date_type": "published", "publication": "PRX Quantum", "volume": "3", "number": "4", "publisher": "American Physical Society", "pagerange": "Art. No. 040318", "id_number": "CaltechAUTHORS:20221202-898320400.1", "issn": "2691-3399", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20221202-898320400.1", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0019374" }, { "agency": "NSF", "grant_number": "CCF-1839204" }, { "agency": "Camille and Henry Dreyfus Foundation" } ] }, "doi": "10.1103/prxquantum.3.040318", "resource_type": "article", "pub_year": "2022", "author_list": "Tazhigulov, Ruslan N.; Sun, Shi-Ning; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/cdd93-v4250", "eprint_id": 116045, "eprint_status": "archive", "datestamp": "2023-08-20 08:05:14", "lastmod": "2023-10-24 20:57:58", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Catherall-David-S", "name": { "family": "Catherall", "given": "David S." }, "orcid": "0000-0002-3540-2419" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "High-field charge transport and noise in p-Si from first principles", "ispublished": "unpub", "full_text_status": "public", "note": "This work was supported by the National Science Foundation under Award No. 1911926. The authors thank A. Choi, B. Hatanp\u00e4\u00e4, P. Cheng, S-N. Sun, and J. Sun for code development and discussions.\n\nSubmitted - 2206.14934.pdf
", "abstract": "The parameter-free computation of charge transport properties of semiconductors is now routine owing to advances in the ab-initio description of the electron-phonon interaction. Many studies focus on the low-field regime in which the carrier temperature equals the lattice temperature and the current power spectral density (PSD) is proportional to the mobility. The calculation of high-field transport and noise properties offers a stricter test of the theory as these relations no longer hold, yet few such calculations have been reported. Here, we compute the high-field mobility and PSD of hot holes in silicon from first principles at temperatures of 77 and 300 K and electric fields up to 20 kV cm\u207b\u00b9 along various crystallographic axes. We find that the calculations quantitatively reproduce experimental trends including the anisotropy and electric-field dependence of hole mobility and PSD. The experimentally observed rapid variation of energy relaxation time with electric field at cryogenic temperatures is also correctly predicted. However, as in low-field studies, absolute quantitative agreement is in general lacking, a discrepancy that has been attributed to inaccuracies in the calculated valence band structure. Our work highlights the use of high-field transport and noise properties as a rigorous test of the theory of electron-phonon interactions in semiconductors.", "date": "2022-08-03", "date_type": "published", "publisher": "arXiv", "id_number": "CaltechAUTHORS:20220802-224606854", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220802-224606854", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "ECCS-1911926" } ] }, "doi": "10.48550/arXiv.2206.14934", "primary_object": { "basename": "2206.14934.pdf", "url": "https://authors.library.caltech.edu/records/cdd93-v4250/files/2206.14934.pdf" }, "resource_type": "monograph", "pub_year": "2022", "author_list": "Catherall, David S. and Minnich, Austin J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/sfrt2-ee072", "eprint_id": 116150, "eprint_status": "archive", "datestamp": "2023-08-22 17:15:44", "lastmod": "2023-10-24 21:00:05", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Wang-Haozhe", "name": { "family": "Wang", "given": "Haozhe" }, "orcid": "0000-0001-5123-1077" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Oxidation-resistant metallic films: Surface engineering at the angstrom scale", "ispublished": "pub", "full_text_status": "restricted", "keywords": "General Materials Science", "note": "\u00a9 2022 Elsevier. \n\nAvailable online 5 August 2022, Version of Record 5 August 2022.", "abstract": "Oxidation-resistant metallic films are of fundamental and practical interest in diverse applications, such as classical and quantum electronics. In a recent paper in Nature, Kim et al. report Cu (111) surfaces which do not oxidize over year timescales owing to their atomic flatness with predominantly mono-atomic steps. This finding highlights how novel functionality of future devices may be achieved through manufacturing with precision at the atomic scale.", "date": "2022-08-03", "date_type": "published", "publication": "Matter", "volume": "5", "number": "8", "publisher": "Cell Press", "pagerange": "2455-2457", "id_number": "CaltechAUTHORS:20220805-204421000", "issn": "2590-2385", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220805-204421000", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1016/j.matt.2022.05.045", "resource_type": "article", "pub_year": "2022", "author_list": "Wang, Haozhe and Minnich, Austin J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/t6abq-j0p36", "eprint_id": 115502, "eprint_status": "archive", "datestamp": "2023-08-20 07:22:26", "lastmod": "2023-10-24 16:32:57", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Tazhigulov-Ruslan-N", "name": { "family": "Tazhigulov", "given": "Ruslan N." }, "orcid": "0000-0002-0679-3078" }, { "id": "Sun-Shi-Ning", "name": { "family": "Sun", "given": "Shi-Ning" }, "orcid": "0000-0002-5984-780X" }, { "id": "Haghshenas-Reza", "name": { "family": "Haghshenas", "given": "Reza" }, "orcid": "0000-0002-5593-8915" }, { "id": "Zhai-Huanchen", "name": { "family": "Zhai", "given": "Huanchen" }, "orcid": "0000-0003-0086-0388" }, { "id": "Tan-Adrian-Teck-Keng", "name": { "family": "Tan", "given": "Adrian T. K." } }, { "id": "Rubin-Nicholas-C", "name": { "family": "Rubin", "given": "Nicholas C." }, "orcid": "0000-0003-3963-1830" }, { "id": "Babbush-Ryan", "name": { "family": "Babbush", "given": "Ryan" }, "orcid": "0000-0001-6979-9533" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" }, { "id": "Chan-Garnet-K-L", "name": { "family": "Chan", "given": "Garnet Kin-Lic" }, "orcid": "0000-0001-8009-6038" } ] }, "title": "Simulating challenging correlated molecules and materials on the Sycamore quantum processor", "ispublished": "unpub", "full_text_status": "public", "note": "R.N.T., R.H., and G.K.-L.C. were supported by the US Department of Energy, Office of Basic Energy Sciences, under Award No. DE-SC0019374. S.-N.S., A.T.K.T, A.J.M were supported by the US NSF under Award No. 1839204. The quantum hardware used in this work was developed by the Google Quantum AI team. Data was collected via cloud access through Google's Quantum Computing Service. The datasheet of the Weber device can be found at http://quantumai.google/hardware/datasheet/weber.pdf. \n\nAuthor contributions. R.N.T., R.H., and G.K.-L.C. conceptualized the project. R.N.T. and S.-N.S. designed and implemented the circuits with help from R.H.. R.N.T. executed the simulations and analyzed the results. R.N.T. and G.K.-L.C. wrote the paper. All authors discussed the results and contributed to the development of the manuscript. \n\nData availability. The data that support the findings of this study are available from the corresponding author upon\nreasonable request. \n\nCode availability. The code used to generate the numerical results presented in this paper can be made available upon reasonable request. \n\nCompeting interests. G.K.-L.C. is a part owner of QSimulate, Inc.\n\nSubmitted - 2203.15291.pdf
", "abstract": "Simulating complex molecules and materials is an anticipated application of quantum devices. With strong quantum advantage demonstrated in artificial tasks, we examine how such advantage translates into modeling physical problems of correlated electronic structure. We simulate static and dynamical electronic structure on a superconducting quantum processor derived from Google's Sycamore architecture for two representative correlated electron problems: the nitrogenase iron-sulfur molecular clusters, and \u03b1-ruthenium trichloride, a proximate spin-liquid material. To do so, we simplify the electronic structure into low-energy spin models that fit on the device. With extensive error mitigation and assistance from classically simulated data, we achieve quantitatively meaningful results deploying about 1/5 of the gate resources used in artificial quantum advantage experiments on a similar architecture. This increases to over 1/2 of the gate resources when choosing a model that suits the hardware. Our work serves to convert artificial measures of quantum advantage into a physically relevant setting.", "date": "2022-07-13", "date_type": "published", "publisher": "arXiv", "id_number": "CaltechAUTHORS:20220712-193849080", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220712-193849080", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0019374" }, { "agency": "NSF", "grant_number": "CCF-1839204" } ] }, "doi": "10.48550/arXiv.2203.15291", "primary_object": { "basename": "2203.15291.pdf", "url": "https://authors.library.caltech.edu/records/t6abq-j0p36/files/2203.15291.pdf" }, "resource_type": "monograph", "pub_year": "2022", "author_list": "Tazhigulov, Ruslan N.; Sun, Shi-Ning; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/j4k9a-zh536", "eprint_id": 115402, "eprint_status": "archive", "datestamp": "2023-08-20 07:40:21", "lastmod": "2023-10-24 16:29:53", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Ardizzi-Anthony-J", "name": { "family": "Ardizzi", "given": "Anthony J." }, "orcid": "0000-0001-8667-1208" }, { "id": "Choi-Alexander-Y", "name": { "family": "Choi", "given": "Alexander Y." }, "orcid": "0000-0003-2006-168X" }, { "id": "Gabritchidze-Bekari", "name": { "family": "Gabritchidze", "given": "Bekari" }, "orcid": "0000-0001-6392-0523" }, { "id": "Kooi-Jacob-W", "name": { "family": "Kooi", "given": "Jacob" }, "orcid": "0000-0002-6610-0384" }, { "id": "Cleary-Kieran-A", "name": { "family": "Cleary", "given": "Kieran A." }, "orcid": "0000-0002-8214-8265" }, { "id": "Readhead-A-C-S", "name": { "family": "Readhead", "given": "Anthony C. S." }, "orcid": "0000-0001-9152-961X" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Self-heating of cryogenic HEMT amplifiers and the limits of microwave\n noise performance", "ispublished": "unpub", "full_text_status": "public", "note": "The authors thank Sander Weinreb, Pekka Kangaslahti, Junjie Li, and Jan Grahn for useful discussions. A.A, A.Y.C., B.G., K.C., A.C.R., and A.J.M. were supported by the National Science Foundation under Grant No. 1911220. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation. J.K. was supported by the Jet Propulsion Laboratory PDRDF under Grant No. 107614-20AW0099. Experimental work was performed at the Cahill Radio Astronomy Laboratory (CRAL) and the Jet Propulsion Laboratory at the California Institute of Technology, under a contract with the National Aeronautics and Space Administration (Grant No. 80NM0018D0004).\n\nSubmitted - 2205.03975.pdf
", "abstract": "The fundamental limits of the microwave noise performance of high electron mobility transistors (HEMTs) are of scientific and practical interest for applications in radio astronomy and quantum computing. Self-heating at cryogenic temperatures has been reported to be a limiting mechanism for the noise, but cryogenic cooling strategies to mitigate it, for instance using liquid cryogens, have not been evaluated. Here, we report microwave noise measurements of a packaged two-stage HEMT amplifier immersed in normal and superfluid \u2074He baths and in vacuum from 1.6 - 80 K. We find that these liquid cryogens are unable to mitigate the thermal noise associated with self-heating. Considering this finding, we examine the implications for the lower bounds of cryogenic noise performance in HEMTs. Our analysis supports the general design principle for cryogenic HEMTs of maximizing gain at the lowest possible power.", "date": "2022-07-08", "date_type": "published", "publisher": "arXiv", "id_number": "CaltechAUTHORS:20220707-204101966", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220707-204101966", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-1911220" }, { "agency": "JPL President and Director's Fund", "grant_number": "107614-20AW0099" }, { "agency": "NASA/JPL/Caltech", "grant_number": "80NM0018D0004" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.48550/arXiv.arXiv.2205.03975", "primary_object": { "basename": "2205.03975.pdf", "url": "https://authors.library.caltech.edu/records/j4k9a-zh536/files/2205.03975.pdf" }, "resource_type": "monograph", "pub_year": "2022", "author_list": "Ardizzi, Anthony J.; Choi, Alexander Y.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/4adhw-rne10", "eprint_id": 112424, "eprint_status": "archive", "datestamp": "2023-08-22 15:29:58", "lastmod": "2023-10-23 22:31:59", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kim-Taeyong", "name": { "family": "Kim", "given": "Taeyong" }, "orcid": "0000-0003-2452-1065" }, { "id": "Drakopoulos-Stavros-X", "name": { "family": "Drakopoulos", "given": "Stavros X." }, "orcid": "0000-0002-6798-0790" }, { "id": "Ronca-Sara", "name": { "family": "Ronca", "given": "Sara" }, "orcid": "0000-0003-3434-6352" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Origin of high thermal conductivity in disentangled ultra-high molecular weight polyethylene films: ballistic phonons within enlarged crystals", "ispublished": "pub", "full_text_status": "public", "keywords": "Organic molecules in materials science; Polymers", "note": "\u00a9 The Author(s) 2022. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. \n\nReceived 04 January 2022; Accepted 06 April 2022; Published 04 May 2022. \n\nThe authors thank Bolin Liao and Wenkai Ouyang for assistance with PPMS measurements. This work was supported by the Office of Naval Research under Grant Number N00014-18-1-2101. \n\nData availability: The authors declare that the data supporting the findings of this study are available within the paper and its Supplementary Material files. \n\nContributions: T.K. and A.J.M. conceived the project. S.X.D. and S.R. fabricated the samples. T.K. performed the TG and PPMS measurements and analyzed the thermal measurements data. All authors discussed the results. T.K. and A.J.M. wrote the manuscript with contributions from all authors. \n\nThe authors declare no competing interests. \n\nPeer review information: Nature Communications thanks Ziqi Liang and the other anonymous reviewer(s) for their contribution to the peer review of this work. Peer review reports are available.\n\nPublished - s41467-022-29904-2.pdf
Submitted - 2111.11318.pdf
Supplemental Material - 41467_2022_29904_MOESM1_ESM.pdf
Supplemental Material - 41467_2022_29904_MOESM2_ESM.pdf
Supplemental Material - 41467_2022_29904_MOESM3_ESM.pdf
", "abstract": "The thermal transport properties of oriented polymers are of fundamental and practical interest. High thermal conductivities (\u2009\u2273\u200950 Wm\u207b\u00b9K\u207b\u00b9) have recently been reported in disentangled ultra-high molecular weight polyethylene (UHMWPE) films, considerably exceeding prior reported values for oriented films. However, conflicting explanations have been proposed for the microscopic origin of the high thermal conductivity. Here, we report a characterization of the thermal conductivity and mean free path accumulation function of disentangled UHMWPE films (draw ratio\u2009~200) using cryogenic steady-state thermal conductivity measurements and transient grating spectroscopy. We observe a marked dependence of the thermal conductivity on grating period over temperatures from 30\u2013300 K. Considering this observation, cryogenic bulk thermal conductivity measurements, and analysis using an anisotropic Debye model, we conclude that longitudinal atomic vibrations with mean free paths around 400 nanometers are the primary heat carriers, and that the high thermal conductivity for draw ratio\u2009\u2273\u2009150 arises from the enlargement of extended crystals with drawing. The mean free paths appear to remain limited by the extended crystal dimensions, suggesting that the upper limit of thermal conductivity of disentangled UHMWPE films has not yet been realized.", "date": "2022-05-04", "date_type": "published", "publication": "Nature Communications", "volume": "13", "publisher": "Nature Publishing Group", "pagerange": "Art. No. 2452", "id_number": "CaltechAUTHORS:20211214-190042892", "issn": "2041-1723", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20211214-190042892", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Office of Naval Research (ONR)", "grant_number": "N00014-18-1-2101" } ] }, "doi": "10.1038/s41467-022-29904-2", "pmcid": "PMC9068786", "primary_object": { "basename": "41467_2022_29904_MOESM2_ESM.pdf", "url": "https://authors.library.caltech.edu/records/4adhw-rne10/files/41467_2022_29904_MOESM2_ESM.pdf" }, "related_objects": [ { "basename": "41467_2022_29904_MOESM3_ESM.pdf", "url": "https://authors.library.caltech.edu/records/4adhw-rne10/files/41467_2022_29904_MOESM3_ESM.pdf" }, { "basename": "s41467-022-29904-2.pdf", "url": "https://authors.library.caltech.edu/records/4adhw-rne10/files/s41467-022-29904-2.pdf" }, { "basename": "2111.11318.pdf", "url": "https://authors.library.caltech.edu/records/4adhw-rne10/files/2111.11318.pdf" }, { "basename": "41467_2022_29904_MOESM1_ESM.pdf", "url": "https://authors.library.caltech.edu/records/4adhw-rne10/files/41467_2022_29904_MOESM1_ESM.pdf" } ], "resource_type": "article", "pub_year": "2022", "author_list": "Kim, Taeyong; Drakopoulos, Stavros X.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/90s7w-h1z55", "eprint_id": 110664, "eprint_status": "archive", "datestamp": "2023-10-04 21:58:25", "lastmod": "2023-10-24 15:33:28", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Esho-Iretomiwa", "name": { "family": "Esho", "given": "Iretomiwa" }, "orcid": "0000-0002-3746-6571" }, { "id": "Choi-Alexander-Y", "name": { "family": "Choi", "given": "Alexander Y." }, "orcid": "0000-0003-2006-168X" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Theory of drain noise in high electron mobility transistors based on real-space transfer", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2022 Published under an exclusive license by AIP Publishing. \n\nSubmitted: 30 August 2021; Accepted: 26 January 2022; Published Online: 28 February 2022. \n\nThe authors thank Jan Grahn and Junjie Li at Chalmers University of Technology for useful discussions and providing the data shown in Fig. 1. I.E. was supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1745301. A.Y.C. and A.J.M. were supported by the National Science Foundation (NSF) under Grant No. 1911220. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation. \n\nThe authors have no conflicts to disclose. \n\nData Availability: The data that support the findings of this study are available from the corresponding author upon reasonable request.\n\nPublished - 085111_1_online.pdf
Submitted - 2108-03370.pdf
", "abstract": "High electron mobility transistors are widely used as microwave amplifiers owing to their low microwave noise figure. Electronic noise in these devices is typically modeled by noise sources at the gate and drain. While consensus exists regarding the origin of the gate noise, that of drain noise is a topic of debate. Here, we report a theory of drain noise as a type of partition noise arising from real-space transfer of hot electrons from the channel to the barrier. The theory accounts for the magnitude and dependencies of the drain temperature and suggests strategies to realize devices with lower noise figure.", "date": "2022-02-28", "date_type": "published", "publication": "Journal of Applied Physics", "volume": "131", "number": "8", "publisher": "American Institute of Physics", "pagerange": "Art. No. 085111", "id_number": "CaltechAUTHORS:20210831-204003339", "issn": "0021-8979", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210831-204003339", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF Graduate Research Fellowship", "grant_number": "DGE-1745301" }, { "agency": "NSF", "grant_number": "AST-1911220" } ] }, "doi": "10.1063/5.0069352", "primary_object": { "basename": "085111_1_online.pdf", "url": "https://authors.library.caltech.edu/records/90s7w-h1z55/files/085111_1_online.pdf" }, "related_objects": [ { "basename": "2108-03370.pdf", "url": "https://authors.library.caltech.edu/records/90s7w-h1z55/files/2108-03370.pdf" } ], "resource_type": "article", "pub_year": "2022", "author_list": "Esho, Iretomiwa; Choi, Alexander Y.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/61hfc-xkx82", "eprint_id": 113522, "eprint_status": "archive", "datestamp": "2023-10-09 20:56:37", "lastmod": "2023-10-24 16:29:14", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lee-Hun", "name": { "family": "Lee", "given": "Hun" }, "orcid": "0000-0003-3304-3712" }, { "id": "Lee-Sehyuk", "name": { "family": "Lee", "given": "Sehyuk" } }, { "id": "So-Soonsung", "name": { "family": "So", "given": "Soonsung" }, "orcid": "0000-0002-4732-3515" }, { "id": "Park-Sang-Hyuk", "name": { "family": "Park", "given": "Sang-Hyuk" }, "orcid": "0000-0001-5166-2352" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" }, { "id": "Lee-Joo-Hyoung", "name": { "family": "Lee", "given": "Joo-Hyoung" }, "orcid": "0000-0002-7637-9825" }, { "id": "Jho-Young-Dahl", "name": { "family": "Jho", "given": "Young-Dahl" }, "orcid": "0000-0002-5898-0406" } ] }, "title": "Enhancing anisotropy of thermal conductivity based on tandem acoustic Bragg reflectors", "ispublished": "pub", "full_text_status": "public", "keywords": "General Physics and Astronomy", "note": "\u00a9 2022 Author(s). Published under an exclusive license by AIP Publishing. \n\nSubmitted: 01 September 2021 \u2022 Accepted: 01 February 2022 \u2022 Published Online: 18 February 2022. \n\nThis research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (No. 2018R1A2B6008101) and the Ministry of Education (No. 2021R1I1A2059710). \n\nDATA AVAILABILITY. The data that support the findings of this study are available from the corresponding author upon reasonable request. \n\nThe authors have no conflicts to disclose.\n\nPublished - 075110_1_online.pdf
", "abstract": "Thermal metamaterials have emerged as one of the latest research topics in applied science due to breakthrough advantages in modifying conductive heat flux. An acoustic Bragg reflector (ABR), composed of alternating arrays of two materials with contrasting acoustic impedances, is anticipated to coherently manipulate the transport properties of thermally important phonon branches by attaining interface roughness close to the monoatomic scale. However, there is a lack of research on how a narrow portion of the phononic band of a particular ABR can be extended to cover the entire thermal spectrum. Here, we report a modeling study of thermal transport using ABR, representatively based on GaAs/AlAs, GaN/AlN, or HfO\u2082/SiO\u2082 superlattices. Our calculations show that the anisotropy of thermal conductivity in HfO\u2082/SiO\u2082 can be significantly improved by tandemizing four different ABR layers, thus approaching the theoretically anticipated values based on monolayered materials. This work demonstrates how the tandem ABR can expand forbidden phononic bands beyond that occupied by a single ABR and proposes a practical strategy for realizing spectrally functionalized thermal properties from compound semiconductor materials that can be directly integrated into the existing device fabrication processes.", "date": "2022-02-21", "date_type": "published", "publication": "Journal of Applied Physics", "volume": "131", "number": "7", "publisher": "American Institute of Physics", "pagerange": "Art. No. 075110", "id_number": "CaltechAUTHORS:20220222-706499000", "issn": "0021-8979", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220222-706499000", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "National Research Foundation of Korea", "grant_number": "2018R1A2B6008101" }, { "agency": "National Research Foundation of Korea", "grant_number": "2021R1I1A2059710" } ] }, "doi": "10.1063/5.0069575", "primary_object": { "basename": "075110_1_online.pdf", "url": "https://authors.library.caltech.edu/records/61hfc-xkx82/files/075110_1_online.pdf" }, "resource_type": "article", "pub_year": "2022", "author_list": "Lee, Hun; Lee, Sehyuk; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/v4ppc-q0v80", "eprint_id": 113332, "eprint_status": "archive", "datestamp": "2023-08-22 13:43:04", "lastmod": "2023-10-23 17:52:04", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kamakari-Hirsh", "name": { "family": "Kamakari", "given": "Hirsh" }, "orcid": "0000-0002-5377-9631" }, { "id": "Sun-Shi-Ning", "name": { "family": "Sun", "given": "Shi-Ning" }, "orcid": "0000-0002-5984-780X" }, { "id": "Motta-Mario", "name": { "family": "Motta", "given": "Mario" }, "orcid": "0000-0003-1647-9864" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Digital Quantum Simulation of Open Quantum Systems Using Quantum Imaginary\u2013Time Evolution", "ispublished": "pub", "full_text_status": "public", "keywords": "General Earth and Planetary Sciences; General Environmental Science", "note": "\u00a9 2022 The Author(s). Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. \n\n(Received 7 June 2021; accepted 11 January 2022; published 4 February 2022) \n\nH.K., S.-N.S., and A.J.M. are supported by the NSF under Grant No. 1839204.\n\nPublished - PRXQuantum.3.010320.pdf
Accepted Version - 2104.07823.pdf
Supplemental Material - supp.pdf
", "abstract": "Quantum simulation on emerging quantum hardware is a topic of intense interest. While many studies focus on computing ground-state properties or simulating unitary dynamics of closed systems, open quantum systems are an interesting target of study owing to their ubiquity and rich physical behavior. However, their nonunitary dynamics are also not natural to simulate on digital quantum devices. Here, we report algorithms for the digital quantum simulation of the dynamics of open quantum systems governed by a Lindblad equation using adaptations of the quantum imaginary\u2013time evolution algorithm. We demonstrate the algorithms on IBM Quantum's hardware with simulations of the spontaneous emission of a two-level system and the dissipative transverse field Ising model. Our work advances efforts to simulate the dynamics of open quantum systems on quantum hardware.", "date": "2022-02", "date_type": "published", "publication": "PRX Quantum", "volume": "3", "number": "1", "publisher": "American Physical Society", "pagerange": "Art. No. 010320", "id_number": "CaltechAUTHORS:20220208-948217000", "issn": "2691-3399", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220208-948217000", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CCF-1839204" } ] }, "doi": "10.1103/prxquantum.3.010320", "primary_object": { "basename": "2104.07823.pdf", "url": "https://authors.library.caltech.edu/records/v4ppc-q0v80/files/2104.07823.pdf" }, "related_objects": [ { "basename": "PRXQuantum.3.010320.pdf", "url": "https://authors.library.caltech.edu/records/v4ppc-q0v80/files/PRXQuantum.3.010320.pdf" }, { "basename": "supp.pdf", "url": "https://authors.library.caltech.edu/records/v4ppc-q0v80/files/supp.pdf" } ], "resource_type": "article", "pub_year": "2022", "author_list": "Kamakari, Hirsh; Sun, Shi-Ning; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/m2bky-wja72", "eprint_id": 113562, "eprint_status": "archive", "datestamp": "2023-08-20 06:51:27", "lastmod": "2023-10-23 23:06:52", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Cheng-Peishi-S", "name": { "family": "Cheng", "given": "Peishi S." }, "orcid": "0000-0002-3513-9972" }, { "id": "Sun-Shi-Ning", "name": { "family": "Sun", "given": "Shi-Ning" }, "orcid": "0000-0002-5984-780X" }, { "id": "Choi-Alexander-Y", "name": { "family": "Choi", "given": "Alexander Y." }, "orcid": "0000-0003-2006-168X" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "High-field transport and hot electron noise in GaAs from first principles: role of two-phonon scattering", "ispublished": "unpub", "full_text_status": "public", "note": "This work was supported by AFOSR under Grant Number FA9550-19-1-0321. The authors thank B. Hatanp\u00e4a\u00e4, D. Catherall and T. Esho for helpful discussions.\n\nAccepted Version - 2201.11912.pdf
", "abstract": "High-field charge transport in semiconductors is of fundamental interest and practical importance. While the ab initio treatment of low-field transport is well-developed, the treatment of high-field transport is much less so, particularly for multi-phonon processes that are reported to be relevant in GaAs. Here, we report a calculation of the high-field transport properties and power spectral density (PSD) of hot electrons in GaAs from first principles including on-shell two-phonon (2ph) scattering. The on-shell 2ph scattering rates are found to qualitatively alter the high-field distribution function by increasing both the momentum and energy relaxation rates as well as contributing markedly to intervalley scattering. This finding reconciles a long-standing discrepancy regarding the strength of intervalley scattering in GaAs as inferred from transport and optical studies. The characteristic non-monotonic trend of PSD with electric field is not predicted at this level of theory, indicating that off-shell 2ph or other processes play a fundamental role in high-field transport. This observation highlights how ab initio calculations of PSD may be used as a stringent test of the electron-phonon interaction in semiconductors.", "date": "2022-01-28", "date_type": "published", "publisher": "arXiv", "id_number": "CaltechAUTHORS:20220223-214559020", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220223-214559020", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-19-1-0321" } ] }, "doi": "10.48550/arXiv.2201.11912", "primary_object": { "basename": "2201.11912.pdf", "url": "https://authors.library.caltech.edu/records/m2bky-wja72/files/2201.11912.pdf" }, "resource_type": "monograph", "pub_year": "2022", "author_list": "Cheng, Peishi S.; Sun, Shi-Ning; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/jbg87-wb743", "eprint_id": 113076, "eprint_status": "archive", "datestamp": "2023-08-20 06:20:29", "lastmod": "2023-10-23 22:54:56", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Tan-Adrian-Teck-Keng", "name": { "family": "Tan", "given": "Adrian T. K." } }, { "id": "Sun-Shi-Ning", "name": { "family": "Sun", "given": "Shi-Ning" }, "orcid": "0000-0002-5984-780X" }, { "id": "Tazhigulov-Ruslan-N", "name": { "family": "Tazhigulov", "given": "Ruslan N." }, "orcid": "0000-0002-0679-3078" }, { "id": "Chan-Garnet-K-L", "name": { "family": "Chan", "given": "Garnet Kin-Lic" }, "orcid": "0000-0001-8009-6038" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Realizing symmetry-protected topological phases in a spin-1/2 chain with next-nearest neighbor hopping on superconducting qubits", "ispublished": "unpub", "full_text_status": "public", "note": "The authors thank M. Wojciech, N. C. Rubin, J. Zhang and R. Babbush for helpful discussions. \n\nA.T.K.T, S.-N.S., A.J.M and G.K.-L.C were supported by the US NSF under Award No. 1839204. R. N. Tazhigulov was supported by the US Department of Energy, Office of Basic Energy Sciences, under Award No. DE-SC0019374. \n\nAuthor contributions: A.T.K.T and A.J.M. conceptualized the project. A.T.K.T designed and optimized the circuit and executed simulations with assistance from S.S. and R.N.T. A.T.K.T carried out the simulation runs on the quantum processor and analyzed the results. A.T.K.T and A.J.M. wrote the paper. All authors discussed the results and contributed to the development of the manuscript. \n\nThe authors declare that they have no competing interests.\n\nSubmitted - 2112.10333.pdf
", "abstract": "The realization of novel phases of matter on quantum simulators is a topic of intense interest. Digital quantum computers offer a route to prepare topological phases with interactions that do not naturally arise in analog quantum simulators. Here, we report the realization of symmetry-protected topological (SPT) phases of a spin-{1/2} Hamiltonian with next-nearest-neighbor hopping on up to 11 qubits on a programmable superconducting quantum processor. We observe clear signatures of the two distinct SPT phases, such as excitations localized to specific edges and finite string order parameters. Our work advances ongoing efforts to realize novel states of matter with exotic interactions on digital near-term quantum computers.", "date": "2022-01-24", "date_type": "published", "publisher": "arXiv", "id_number": "CaltechAUTHORS:20220124-192944633", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220124-192944633", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CCF-1839204" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0019374" } ] }, "doi": "10.48550/arXiv.2112.10333", "primary_object": { "basename": "2112.10333.pdf", "url": "https://authors.library.caltech.edu/records/jbg87-wb743/files/2112.10333.pdf" }, "resource_type": "monograph", "pub_year": "2022", "author_list": "Tan, Adrian T. K.; Sun, Shi-Ning; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/cas1r-mv144", "eprint_id": 112684, "eprint_status": "archive", "datestamp": "2023-10-09 15:35:31", "lastmod": "2023-10-24 16:28:18", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Park-Sang-Hyuk", "name": { "family": "Park", "given": "Sang-Hyuk" }, "orcid": "0000-0001-5166-2352" }, { "id": "Lee-Hun", "name": { "family": "Lee", "given": "Hun" }, "orcid": "0000-0003-3304-3712" }, { "id": "Lee-Sehyuk", "name": { "family": "Lee", "given": "Sehyuk" } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" }, { "id": "Jeong-Woo-Lim", "name": { "family": "Jeong", "given": "Woo-Lim" }, "orcid": "0000-0002-6445-0583" }, { "id": "Lee-Dong-Seon", "name": { "family": "Lee", "given": "Dong-Seon" }, "orcid": "0000-0003-2706-8702" }, { "id": "So-Soon-Sung", "name": { "family": "So", "given": "Soon-Sung" }, "orcid": "0000-0002-4732-3515" }, { "id": "Lee-Joo-Hyoung", "name": { "family": "Lee", "given": "Joo-Hyoung" }, "orcid": "0000-0002-7637-9825" }, { "id": "Min-Song-Young", "name": { "family": "Min Song", "given": "Young" }, "orcid": "0000-0002-4473-6883" }, { "id": "Jho-Young-Dahl", "name": { "family": "Jho", "given": "Young-Dahl" }, "orcid": "0000-0002-5898-0406" } ] }, "title": "Annealing-based manipulation of thermal phonon transport from light-emitting diodes to graphene", "ispublished": "pub", "full_text_status": "public", "keywords": "General Physics and Astronomy", "note": "\u00a9 2021 Author(s). Published under an exclusive license by AIP Publishing. \n\nSubmitted: 31 August 2021; Accepted: 02 December 2021; Published Online: 27 December 2021.\n\nPaper published as part of the special topic on Engineering and Understanding of Thermal Conduction in Materials. \n\nThis research was supported by the Korea Electric Power Corporation (No. R17XA05-64), the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning (No. 2018R1A2B6008101), and the Ministry of Education (No. 2021R1I1A2059710). \n\nThe authors have no conflicts to disclose. \n\nDATA AVAILABILITY. The data that support the findings of this study are available from the corresponding author upon reasonable request.\n\nPublished - 244303_1_online.pdf
", "abstract": "We demonstrate that the thermal boundary conductivity (TBC) between graphene and GaN-based light-emitting diodes (LEDs) can be manipulated through thermal annealing, which is verified by measuring the acoustic phonons after reflection at the interface. Thermal annealing affects the interfacial morphology as evaluated by both the Raman spectra and the spatial profile of the graphene wrinkles in atomic force microscopy. By tracing the phase of ultrafast acoustic oscillations on the basis of the pump-probe scheme, we extract the phonon reflection coefficient at the interface as a function of annealing temperatures up to 400\u2009\u2218C. Specifically, the phase shift of transient phononic oscillations at the graphene/LED interface conveys the photoelastic response during the phonon transfer process and can be used for extracting the interfacial coupling rate, which is strongly enhanced around \u2248200\u2218C. By incorporating the heat capacity and the interfacial coupling constants into TBC, along with analytical modeling based on the phonon reflection coefficients, we show that the TBC increases with the minimized surface roughness of graphene side at 200\u2009\u2218C. This new comprehensive TBC extraction scheme could spark further discussion on improving the heat dissipation of LEDs.", "date": "2021-12-28", "date_type": "published", "publication": "Journal of Applied Physics", "volume": "130", "number": "24", "publisher": "American Institute of Physics", "pagerange": "Art. No. 244303", "id_number": "CaltechAUTHORS:20220104-157929000", "issn": "0021-8979", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220104-157929000", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Korea Electric Power Corporation", "grant_number": "R17XA05-64" }, { "agency": "National Research Foundation of Korea", "grant_number": "2018R1A2B6008101" }, { "agency": "National Research Foundation of Korea", "grant_number": "2021R1I1A2059710" } ] }, "doi": "10.1063/5.0069466", "primary_object": { "basename": "244303_1_online.pdf", "url": "https://authors.library.caltech.edu/records/cas1r-mv144/files/244303_1_online.pdf" }, "resource_type": "article", "pub_year": "2021", "author_list": "Park, Sang-Hyuk; Lee, Hun; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/spvmg-pa513", "eprint_id": 109428, "eprint_status": "archive", "datestamp": "2023-08-22 11:57:21", "lastmod": "2023-10-23 17:56:30", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Drakopoulos-Stavros-X", "name": { "family": "Drakopoulos", "given": "Stavros X." }, "orcid": "0000-0002-6798-0790" }, { "id": "Manika-Georgia-C", "name": { "family": "Manika", "given": "Georgia C." } }, { "id": "Nogales-Aurora", "name": { "family": "Nogales", "given": "Aurora" }, "orcid": "0000-0002-2494-3551" }, { "id": "Kim-Taeyong", "name": { "family": "Kim", "given": "Taeyong" } }, { "id": "Robbins-Andrew-B", "name": { "family": "Robbins", "given": "Andrew B." } }, { "id": "Claudio-Gianfranco", "name": { "family": "Claudio", "given": "Gianfranco" } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" }, { "id": "Ezquerra-Tiberio-A", "name": { "family": "Ezquerra", "given": "Tiberio A." }, "orcid": "0000-0001-9966-519X" }, { "id": "Psarras-Georgios-C", "name": { "family": "Psarras", "given": "Georgios C." }, "orcid": "0000-0002-0539-2838" }, { "id": "Martin\u2010Fabiani-Ignacio", "name": { "family": "Martin\u2010Fabiani", "given": "Ignacio" }, "orcid": "0000-0002-1977-7659" }, { "id": "Ronca-Sara", "name": { "family": "Ronca", "given": "Sara" }, "orcid": "0000-0003-3434-6352" } ] }, "title": "Gold/ultra-high molecular weight polyethylene nanocomposites for electrical energy storage: Enhanced recovery efficiency upon uniaxial deformation", "ispublished": "pub", "full_text_status": "public", "keywords": "dielectric properties; energy storage; nanocomposites; polyolefins; thermal properties", "note": "\u00a9 2021 The Authors. Journal of Applied Polymer Science published by Wiley Periodicals LLC. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. \n\nIssue Online: 02 August 2021; Version of Record online: 02 June 2021; Manuscript accepted: 23 May 2021; Manuscript revised: 20 May 2021; Manuscript received: 15 February 2021. \n\nThe authors would like to thank Dr Giuseppe Forte for the chemical synthesis of the dis-UHMWPE powder. This project has been funded by the Engineering and Physical Science Research Council (EPSRC), grant EP/K034405/1.\n\nPublished - app.51232.pdf
Supplemental Material - app51232-sup-0001-supinfo.docx
", "abstract": "The growing demand for renewable energy sources has prompted the development of dielectric materials with the ability to store and efficiently recover electrical energy. Here, we correlate the structure and thermal conductivity of uniaxially oriented disentangled ultra-high molecular weight polyethylene (dis-UHMWPE) composites reinforced with gold nanoparticles with their electrical properties and potential application as electrical energy storage devices. Stretching increases the orientation of the polymer chains and thus the crystallinity and reduces the aggregation of gold nanoparticles while the thermal conductivity enhances significantly along the orientation axis. The structural changes driven by stretching result in two competing effects; on the one hand, the crystallinity increase reduces the permittivity of the composites and increases the resistivity, while on the other hand the recovery efficiency of oriented materials excels that of unstretched samples by up to 6 times at 5 s. Therefore, our work shows the structure\u2013property relationship in electrical energy storage materials.", "date": "2021-11-10", "date_type": "published", "publication": "Journal of Applied Polymer Science", "volume": "138", "number": "42", "publisher": "Wiley", "pagerange": "Art. No. 51232", "id_number": "CaltechAUTHORS:20210608-071948726", "issn": "0021-8995", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210608-071948726", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Engineering and Physical Sciences Research Council (EPSRC)", "grant_number": "EP/K034405/1" } ] }, "doi": "10.1002/app.51232", "primary_object": { "basename": "app51232-sup-0001-supinfo.docx", "url": "https://authors.library.caltech.edu/records/spvmg-pa513/files/app51232-sup-0001-supinfo.docx" }, "related_objects": [ { "basename": "app.51232.pdf", "url": "https://authors.library.caltech.edu/records/spvmg-pa513/files/app.51232.pdf" } ], "resource_type": "article", "pub_year": "2021", "author_list": "Drakopoulos, Stavros X.; Manika, Georgia C.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/5gfsk-0r921", "eprint_id": 109794, "eprint_status": "archive", "datestamp": "2023-10-04 21:56:32", "lastmod": "2023-10-24 15:33:07", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Naik-Nachiket-R", "name": { "family": "Naik", "given": "Nachiket R." }, "orcid": "0000-0001-8271-643X" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Quasiballistic electron transport in cryogenic SiGe HBTs studied using an exact, semi-analytic solution to the Boltzmann equation", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2021 Published under an exclusive license by AIP Publishing. \n\nSubmitted: 12 July 2021; Accepted: 29 September 2021; Published Online: 1 November 2021. \n\nThe authors thank Mark Lundstrom, J. P. Peraud, and Nicolas Hadjiconstantinou for useful discussions. This work was supported by the National Science Foundation (NSF) (Award No. 1911926). \n\nThe authors have no conflicts to disclose. \n\nData Availability: The data that support the findings of this study are available from the corresponding author upon reasonable request.\n\nPublished - 174504_1_online.pdf
Submitted - 2106-05374.pdf
", "abstract": "Silicon\u2013germanium heterojunction bipolar transistors (HBTs) are of interest as low-noise microwave amplifiers due to their competitive noise performance and low cost relative to III\u2013V devices. The fundamental noise performance limits of HBTs are thus of interest, and several studies report that quasiballistic electron transport across the base is a mechanism leading to cryogenic non-ideal IV characteristics that affect these limits. However, this conclusion has not been rigorously tested against theoretical predictions because prior studies modeled electron transport with empirical approaches or approximate solutions of the Boltzmann equation. Here, we study non-diffusive transport in narrow-base SiGe HBTs using an exact, semi-analytic solution of the Boltzmann equation based on an asymptotic expansion approach. We find that the computed transport characteristics are inconsistent with experiments, implying that quasiballistic electron transport is unlikely to be the origin of cryogenic non-ideal IV characteristics. Our work helps to identify the mechanisms governing the lower limits of the microwave noise figure of cryogenic HBT amplifiers.", "date": "2021-11-07", "date_type": "published", "publication": "Journal of Applied Physics", "volume": "130", "number": "17", "publisher": "American Institute of Physics", "pagerange": "Art. No. 174504", "id_number": "CaltechAUTHORS:20210713-213714240", "issn": "0021-8979", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210713-213714240", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "ECCS-1911926" } ] }, "doi": "10.1063/5.0063178", "primary_object": { "basename": "174504_1_online.pdf", "url": "https://authors.library.caltech.edu/records/5gfsk-0r921/files/174504_1_online.pdf" }, "related_objects": [ { "basename": "2106-05374.pdf", "url": "https://authors.library.caltech.edu/records/5gfsk-0r921/files/2106-05374.pdf" } ], "resource_type": "article", "pub_year": "2021", "author_list": "Naik, Nachiket R. and Minnich, Austin J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/5qt1q-2y624", "eprint_id": 111767, "eprint_status": "archive", "datestamp": "2023-10-05 22:28:08", "lastmod": "2023-10-24 16:25:11", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Choi-Alexander-Y", "name": { "family": "Choi", "given": "Alexander Y." }, "orcid": "0000-0003-2006-168X" }, { "id": "Esho-Iretomiwa", "name": { "family": "Esho", "given": "Iretomiwa" }, "orcid": "0000-0002-3746-6571" }, { "id": "Gabritchidze-Bekari", "name": { "family": "Gabritchidze", "given": "Bekari" }, "orcid": "0000-0001-6392-0523" }, { "id": "Kooi-Jacob-W", "name": { "family": "Kooi", "given": "Jacob" }, "orcid": "0000-0002-6610-0384" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Characterization of self-heating in cryogenic high electron mobility transistors using Schottky thermometry", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2021 Published under an exclusive license by AIP Publishing. \n\nSubmitted: 14 July 2021; Accepted: 29 September 2021; Published Online: 21 October 2021. \n\nA.Y.C., B.G., and A.J.M. were supported by the National Science Foundation under Grant No. 1911220. I.E. was supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1745301. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation. J.K. and A.J.M. were supported by the Jet Propulsion Laboratory PDRDF under Grant No. 107614-20AW0099. Experimental work was performed at the Cahill Radio Astronomy Laboratory (CRAL) and the Jet Propulsion Laboratory at the California Institute of Technology, under a contract with the National Aeronautics and Space Administration (Grant No. 80NM0018D0004). \n\nData Availability: The data that support the findings of this study are available from the corresponding author upon reasonable request.\n\nPublished - 155107_1_online.pdf
Submitted - 2105-11571.pdf
", "abstract": "Cryogenic low-noise amplifiers based on high electron mobility transistors (HEMTs) are widely used in applications such as radio astronomy, deep space communications, and quantum computing. Consequently, the physical mechanisms governing the microwave noise figure are of practical interest. In particular, the magnitude of the contribution of thermal noise from the gate at cryogenic temperatures remains unclear owing to a lack of experimental measurements of thermal resistance under these conditions. Here, we report measurements of gate junction temperature and thermal resistance in a HEMT at cryogenic and room temperatures using Schottky thermometry. At temperatures \u223c20\u2009K, we observe a nonlinear trend of thermal resistance vs power that is consistent with heat dissipation by phonon radiation. Based on this finding, we consider heat transport by phonon radiation at the low-noise bias and liquid helium temperatures and estimate that the thermal noise from the gate is several times larger than previously assumed owing to self-heating. We conclude that without improvements in thermal management, self-heating results in a practical lower limit for microwave noise figure of HEMTs at cryogenic temperatures.", "date": "2021-10-21", "date_type": "published", "publication": "Journal of Applied Physics", "volume": "130", "number": "15", "publisher": "American Institute of Physics", "pagerange": "Art. No. 155107", "id_number": "CaltechAUTHORS:20211105-172920271", "issn": "0021-8979", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20211105-172920271", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-1911220" }, { "agency": "NSF Graduate Research Fellowship", "grant_number": "DGE-1745301" }, { "agency": "JPL", "grant_number": "107614-20AW0099" }, { "agency": "NASA", "grant_number": "80NM0018D0004" } ] }, "doi": "10.1063/5.0063331", "primary_object": { "basename": "155107_1_online.pdf", "url": "https://authors.library.caltech.edu/records/5qt1q-2y624/files/155107_1_online.pdf" }, "related_objects": [ { "basename": "2105-11571.pdf", "url": "https://authors.library.caltech.edu/records/5qt1q-2y624/files/2105-11571.pdf" } ], "resource_type": "article", "pub_year": "2021", "author_list": "Choi, Alexander Y.; Esho, Iretomiwa; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/cnnkx-qkd93", "eprint_id": 105081, "eprint_status": "archive", "datestamp": "2023-08-20 03:23:17", "lastmod": "2023-10-20 21:20:31", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kim-Taeyong", "name": { "family": "Kim", "given": "Taeyong" }, "orcid": "0000-0003-2452-1065" }, { "id": "Moon-Jaeyun", "name": { "family": "Moon", "given": "Jaeyun" } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Origin of micrometer-scale propagation lengths of heat-carrying acoustic excitations in amorphous silicon", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2021 American Physical Society. \n\nReceived 22 July 2020; revised 5 March 2021; accepted 27 April 2021; published 9 June 2021. \n\nThe authors acknowledge discussions with A. B. Robbins and B. C. Daly. This work was supported by the 2018 GIST-Caltech Research Collaboration.\n\nPublished - PhysRevMaterials.5.065602.pdf
Submitted - 2007.15777.pdf
Supplemental Material - SI_PRM.pdf
", "abstract": "The heat-carrying acoustic excitations of amorphous silicon are of interest because their mean free paths may approach micron scales at room temperature. Despite extensive investigation, the origin of the weak acoustic scattering in the heat-carrying frequencies remains a topic of debate. Here, we report measurements of the thermal conductivity mean free path accumulation function in amorphous silicon thin films from 60 to 315 K using transient grating spectroscopy. With additional picosecond acoustics measurements and considering the power-law frequency dependence of scattering mechanisms in glasses, we reconstruct the mean free paths from \u223c0.1\u20133 THz. The mean free paths are independent of temperature and exhibit a Rayleigh scattering trend over most of this frequency range. The observed trend is inconsistent with the predictions of numerical studies based on normal mode analysis but agrees with diverse measurements on other glasses. The micron-scale MFPs in amorphous Si arise from the absence of anharmonic or thermally activated relaxation damping in the sub-THz frequencies, leading to heat-carrying acoustic excitations with room-temperature MFPs comparable to those of other glasses at cryogenic temperatures.", "date": "2021-06", "date_type": "published", "publication": "Physical Review Materials", "volume": "5", "number": "6", "publisher": "American Physical Society", "pagerange": "Art. No. 065602", "id_number": "CaltechAUTHORS:20200824-140943584", "issn": "2475-9953", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200824-140943584", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "GIST-Caltech Research Collaboration" } ] }, "doi": "10.1103/PhysRevMaterials.5.065602", "primary_object": { "basename": "2007.15777.pdf", "url": "https://authors.library.caltech.edu/records/cnnkx-qkd93/files/2007.15777.pdf" }, "related_objects": [ { "basename": "PhysRevMaterials.5.065602.pdf", "url": "https://authors.library.caltech.edu/records/cnnkx-qkd93/files/PhysRevMaterials.5.065602.pdf" }, { "basename": "SI_PRM.pdf", "url": "https://authors.library.caltech.edu/records/cnnkx-qkd93/files/SI_PRM.pdf" } ], "resource_type": "article", "pub_year": "2021", "author_list": "Kim, Taeyong; Moon, Jaeyun; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/gqdh4-0kp36", "eprint_id": 90459, "eprint_status": "archive", "datestamp": "2023-08-22 09:56:16", "lastmod": "2023-10-18 23:28:01", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Motta-Mario", "name": { "family": "Motta", "given": "Mario" }, "orcid": "0000-0003-1647-9864" }, { "id": "Ye-Erika", "name": { "family": "Ye", "given": "Erika" }, "orcid": "0000-0001-9694-568X" }, { "id": "McClean-Jarrod-R", "name": { "family": "McClean", "given": "Jarrod R." } }, { "id": "Li-Zhendong", "name": { "family": "Li", "given": "Zhendong" }, "orcid": "0000-0002-0683-6293" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" }, { "id": "Babbush-Ryan", "name": { "family": "Babbush", "given": "Ryan" }, "orcid": "0000-0001-6979-9533" }, { "id": "Chan-Garnet-K-L", "name": { "family": "Chan", "given": "Garnet Kin-Lic" }, "orcid": "0000-0001-8009-6038" } ] }, "title": "Low rank representations for quantum simulation of electronic structure", "ispublished": "pub", "full_text_status": "public", "keywords": "Quantum information; Quantum simulation", "note": "\u00a9 The Author(s) 2021. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. \n\nReceived 02 September 2020; Accepted 19 April 2021; Published 27 May 2021. \n\nM.M. gratefully acknowledges Shiwei Zhang and James Shee for valuable interactions. M.M., Z.L., and G.K.C. (theoretical analysis, electronic structure calculations, drafting of the paper) were supported by NSF grant number 1839204. E.Y. (gate counts, electronic structure calculations) was supported by a Google graduate fellowship and a Google award to G.K.C. A.M. (drafting of the paper) was supported by NSF grant CBET CAREER number 1254213. \n\nData availability: Data regarding the electronic structure calculations can be provided upon request. The matrix elements h_(pq), h_(pqrs) for the iron\u2013sulfur cluster are made available in a compressed archive form (FeS_integrals.tar). \n\nCode availability: Code performing the double-decomposition and electronic structure calculations are available upon request. PySCF is available on GitHub (https://github.com/pyscf/pyscf). \n\nAuthor Contributions: R.B., G.K.C., and M.M. contributed to the conception of the project; M.M., J.R.M., Z.L., R.B., and G.K.C. contributed to the theoretical analysis; M.M., Z.L., E.Y., and G.K.C. contributed to the electronic structure calculations; M.M., J.R.M., E.Y., R.B., and G.K.C. contributed to the gate counts analysis. All authors contributed to the drafting of the paper. \n\nThe authors declare no competing interests.\n\nPublished - s41534-021-00416-z.pdf
Submitted - 1808.02625.pdf
Supplemental Material - 41534_2021_416_MOESM1_ESM.gz
Supplemental Material - 41534_2021_416_MOESM2_ESM.pdf
", "abstract": "The quantum simulation of quantum chemistry is a promising application of quantum computers. However, for N molecular orbitals, the O(N\u2074) gate complexity of performing Hamiltonian and unitary Coupled Cluster Trotter steps makes simulation based on such primitives challenging. We substantially reduce the gate complexity of such primitives through a two-step low-rank factorization of the Hamiltonian and cluster operator, accompanied by truncation of small terms. Using truncations that incur errors below chemical accuracy allow one to perform Trotter steps of the arbitrary basis electronic structure Hamiltonian with O(N\u00b3) gate complexity in small simulations, which reduces to O(N\u00b2) gate complexity in the asymptotic regime; and unitary Coupled Cluster Trotter steps with O(N\u00b3) gate complexity as a function of increasing basis size for a given molecule. In the case of the Hamiltonian Trotter step, these circuits have O(N\u00b2) depth on a linearly connected array, an improvement over the O(N\u00b3) scaling assuming no truncation. As a practical example, we show that a chemically accurate Hamiltonian Trotter step for a 50 qubit molecular simulation can be carried out in the molecular orbital basis with as few as 4000 layers of parallel nearest-neighbor two-qubit gates, consisting of fewer than 10\u2075 non-Clifford rotations. We also apply our algorithm to iron\u2013sulfur clusters relevant for elucidating the mode of action of metalloenzymes.", "date": "2021-05-27", "date_type": "published", "publication": "npj Quantum Information", "volume": "7", "publisher": "Nature Publishing Group", "pagerange": "Art. No. 83", "id_number": "CaltechAUTHORS:20181029-100728436", "issn": "2056-6387", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181029-100728436", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CCF-1839204" }, { "agency": "Google" }, { "agency": "NSF", "grant_number": "CBET-1254213" } ] }, "doi": "10.1038/s41534-021-00416-z", "primary_object": { "basename": "1808.02625.pdf", "url": "https://authors.library.caltech.edu/records/gqdh4-0kp36/files/1808.02625.pdf" }, "related_objects": [ { "basename": "41534_2021_416_MOESM1_ESM.gz", "url": "https://authors.library.caltech.edu/records/gqdh4-0kp36/files/41534_2021_416_MOESM1_ESM.gz" }, { "basename": "41534_2021_416_MOESM2_ESM.pdf", "url": "https://authors.library.caltech.edu/records/gqdh4-0kp36/files/41534_2021_416_MOESM2_ESM.pdf" }, { "basename": "s41534-021-00416-z.pdf", "url": "https://authors.library.caltech.edu/records/gqdh4-0kp36/files/s41534-021-00416-z.pdf" } ], "resource_type": "article", "pub_year": "2021", "author_list": "Motta, Mario; Ye, Erika; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ag1t6-af884", "eprint_id": 106142, "eprint_status": "archive", "datestamp": "2023-08-20 02:28:23", "lastmod": "2023-10-20 23:08:01", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Choi-Alexander-Y", "name": { "family": "Choi", "given": "Alexander Y." }, "orcid": "0000-0003-2006-168X" }, { "id": "Cheng-Peishi-S", "name": { "family": "Cheng", "given": "Peishi S." }, "orcid": "0000-0002-3513-9972" }, { "id": "Hatanp\u00e4\u00e4-Benjamin", "name": { "family": "Hatanp\u00e4\u00e4", "given": "Benjamin" }, "orcid": "0000-0002-8441-0183" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Electronic noise of warm electrons in semiconductors from first principles", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2021 American Physical Society. \n\nReceived 23 September 2020; revised 25 January 2021; accepted 1 March 2021; published 6 April 2021. \n\nThe authors thank Jin-Jian Zhou, I-Te Lu, Vatsal Jhalani, and Marco Bernardi for assistance with Perturbo and useful discussions. This work was supported by AFOSR under Grant No. FA9550-19-1-0321. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1745301. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author and do not necessarily reflect the views of the National Science Foundation.\n\nPublished - PhysRevMaterials.5.044603.pdf
Submitted - 2009.11395.pdf
", "abstract": "The ab initio theory of low-field electronic transport properties such as carrier mobility in semiconductors is well-established. However, an equivalent treatment of electronic fluctuations about a nonequilibrium steady state, which are readily probed experimentally, remains less explored. Here, we report a first-principles theory of electronic noise for warm electrons in semiconductors. In contrast with typical numerical methods used for electronic noise, no adjustable parameters are required in the present formalism, with the electronic band structure and scattering rates calculated from first principles. We demonstrate the utility of our approach by applying it to GaAs and show that spectral features in AC transport properties and noise originate from the disparate time scales of momentum and energy relaxation, despite the dominance of optical phonon scattering. Our formalism enables a parameter-free approach to probe the microscopic transport processes that give rise to electronic noise in semiconductors.", "date": "2021-04", "date_type": "published", "publication": "Physical Review Materials", "volume": "5", "number": "4", "publisher": "American Physical Society", "pagerange": "Art. No. 044603", "id_number": "CaltechAUTHORS:20201019-101209881", "issn": "2475-9953", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20201019-101209881", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-19-1-0321" }, { "agency": "NSF Graduate Research Fellowship", "grant_number": "DGE-1745301" } ] }, "doi": "10.1103/PhysRevMaterials.5.044603", "primary_object": { "basename": "PhysRevMaterials.5.044603.pdf", "url": "https://authors.library.caltech.edu/records/ag1t6-af884/files/PhysRevMaterials.5.044603.pdf" }, "related_objects": [ { "basename": "2009.11395.pdf", "url": "https://authors.library.caltech.edu/records/ag1t6-af884/files/2009.11395.pdf" } ], "resource_type": "article", "pub_year": "2021", "author_list": "Choi, Alexander Y.; Cheng, Peishi S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/bnpgk-00804", "eprint_id": 106319, "eprint_status": "archive", "datestamp": "2023-08-20 01:39:29", "lastmod": "2023-10-20 23:20:48", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sun-Shi-Ning", "name": { "family": "Sun", "given": "Shi-Ning" }, "orcid": "0000-0002-5984-780X" }, { "id": "Motta-Mario", "name": { "family": "Motta", "given": "Mario" }, "orcid": "0000-0003-1647-9864" }, { "id": "Tazhigulov-Ruslan-N", "name": { "family": "Tazhigulov", "given": "Ruslan N." }, "orcid": "0000-0002-0679-3078" }, { "id": "Tan-Adrian-Teck-Keng", "name": { "family": "Tan", "given": "Adrian T. K." } }, { "id": "Chan-Garnet-K-L", "name": { "family": "Chan", "given": "Garnet Kin-Lic" }, "orcid": "0000-0001-8009-6038" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Quantum Computation of Finite-Temperature Static and Dynamical Properties of Spin Systems Using Quantum Imaginary Time Evolution", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2021 Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. \n\nReceived 9 September 2020; accepted 28 November 2020; published 1 February 2021. \n\nThe authors thank Y. Wang, X. Ma, S. Sheldon and T. P. Gujarati for helpful discussions. S.-N.S., A.T.K.T., and A.J.M. are supported by NSF Grant No. 1839204. R.N.T. and G.K.-L.C. are supported by the US Department of Energy, Office of Science, Grant No. 19374. S.-N.S. acknowledges J. M. Burks and G. O. Jones for helping with access to IBM Quantum devices.\n\nPublished - PRXQuantum.2.010317.pdf
Submitted - 2009.03542.pdf
", "abstract": "Developing scalable quantum algorithms to study finite-temperature physics of quantum many-body systems has attracted considerable interest due to recent advancements in quantum hardware. However, such algorithms in their present form require resources that exceed the capabilities of current quantum computers except for a limited range of system sizes and observables. Here, we report calculations of finite-temperature properties, including energy, static and dynamical correlation functions, and excitation spectra of spin systems with up to four sites on five-qubit IBM Quantum devices. These calculations are performed using the quantum imaginary time evolution (QITE) algorithm and made possible by several algorithmic improvements, including a method to exploit symmetries that reduces the quantum resources required by QITE, circuit optimization procedures to reduce circuit depth, and error-mitigation techniques to improve the quality of raw hardware data. Our work demonstrates that the ansatz-independent QITE algorithm is capable of computing diverse finite-temperature observables on near-term quantum devices.", "date": "2021-02", "date_type": "published", "publication": "PRX Quantum", "volume": "2", "number": "1", "publisher": "American Physical Society", "pagerange": "Art. No. 010317", "id_number": "CaltechAUTHORS:20201028-084640144", "issn": "2691-3399", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20201028-084640144", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CCF-1839204" }, { "agency": "Department of Energy (DOE)", "grant_number": "19374" } ] }, "doi": "10.1103/PRXQuantum.2.010317", "primary_object": { "basename": "2009.03542.pdf", "url": "https://authors.library.caltech.edu/records/bnpgk-00804/files/2009.03542.pdf" }, "related_objects": [ { "basename": "PRXQuantum.2.010317.pdf", "url": "https://authors.library.caltech.edu/records/bnpgk-00804/files/PRXQuantum.2.010317.pdf" } ], "resource_type": "article", "pub_year": "2021", "author_list": "Sun, Shi-Ning; Motta, Mario; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/0e3pd-x5163", "eprint_id": 106281, "eprint_status": "archive", "datestamp": "2023-08-20 01:01:36", "lastmod": "2023-10-20 23:18:31", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "White-Alec-F", "name": { "family": "White", "given": "Alec F." }, "orcid": "0000-0002-9743-1469" }, { "id": "Gao-Yang", "name": { "family": "Gao", "given": "Yang" }, "orcid": "0000-0003-2320-2839" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" }, { "id": "Chan-Garnet-K-L", "name": { "family": "Chan", "given": "Garnet Kin-Lic" }, "orcid": "0000-0001-8009-6038" } ] }, "title": "A coupled cluster framework for electrons and phonons", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2020 Published under license by AIP Publishing. \n\nSubmitted: 13 October 2020; Accepted: 24 November 2020; Published Online: 9 December 2020. \n\nWe thank Jinjian Zhou for helpful discussion in the implementation of ab initio EPI matrix using cGTO basis. A.F.W. and G.K.-L.C. acknowledge support from the U.S. Department of Energy via the M2QM EFRC under Award No. de-sc0019330. Y.G. and A.J.M. acknowledge the support of ONR under Grant No. N00014-18-1-2101. \n\nAuthor Contributions: A.F.W. and Y.G. contributed equally to this work.\n\nPublished - 5.0033132.pdf
Submitted - 2009.13568.pdf
", "abstract": "We describe a coupled cluster framework for coupled systems of electrons and harmonic phonons. Neutral and charged excitations are accessed via the equation-of-motion version of the theory. Benchmarks on the Hubbard\u2013Holstein model allow us to assess the strengths and weaknesses of different coupled cluster approximations, which generally perform well for weak to moderate coupling. Finally, we report progress toward an implementation for ab initio calculations on solids and present some preliminary results on finite-size models of diamond with a linear electron\u2013phonon coupling. We also report the implementation of electron\u2013phonon coupling matrix elements from crystalline Gaussian type orbitals within the PySCF program package.", "date": "2020-12-14", "date_type": "published", "publication": "Journal of Chemical Physics", "volume": "153", "number": "22", "publisher": "American Institute of Physics", "pagerange": "Art. No. 224112", "id_number": "CaltechAUTHORS:20201026-152806389", "issn": "0021-9606", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20201026-152806389", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0019330" }, { "agency": "Office of Naval Research (ONR)", "grant_number": "N00014-18-1-2101" } ] }, "doi": "10.1063/5.0033132", "primary_object": { "basename": "2009.13568.pdf", "url": "https://authors.library.caltech.edu/records/0e3pd-x5163/files/2009.13568.pdf" }, "related_objects": [ { "basename": "5.0033132.pdf", "url": "https://authors.library.caltech.edu/records/0e3pd-x5163/files/5.0033132.pdf" } ], "resource_type": "article", "pub_year": "2020", "author_list": "White, Alec F.; Gao, Yang; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/1kpda-78s09", "eprint_id": 106874, "eprint_status": "archive", "datestamp": "2023-08-22 07:42:32", "lastmod": "2023-10-23 15:08:22", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sun-Bo", "name": { "family": "Sun", "given": "Bo" }, "orcid": "0000-0002-2122-6637" }, { "id": "Niu-Shanyuan", "name": { "family": "Niu", "given": "Shanyuan" } }, { "id": "Hermann-Rapha\u00ebl-P", "name": { "family": "Hermann", "given": "Rapha\u00ebl P." }, "orcid": "0000-0002-6138-5624" }, { "id": "Moon-Jaeyun", "name": { "family": "Moon", "given": "Jaeyun" }, "orcid": "0000-0003-0128-4108" }, { "id": "Shulumba-Nina", "name": { "family": "Shulumba", "given": "Nina" }, "orcid": "0000-0002-2374-7487" }, { "id": "Page-Katharine", "name": { "family": "Page", "given": "Katharine" }, "orcid": "0000-0002-9071-3383" }, { "id": "Zhao-Boyang", "name": { "family": "Zhao", "given": "Boyang" } }, { "id": "Thind-Arashdeep-S", "name": { "family": "Thind", "given": "Arashdeep S." } }, { "id": "Mahalingam-Krishnamurthy", "name": { "family": "Mahalingam", "given": "Krishnamurthy" } }, { "id": "Milam-Guerrero-JoAnna", "name": { "family": "Milam-Guerrero", "given": "JoAnna" }, "orcid": "0000-0002-1533-0251" }, { "id": "Haiges-Ralf", "name": { "family": "Haiges", "given": "Ralf" }, "orcid": "0000-0003-4151-3593" }, { "id": "Mecklenburg-Matthew", "name": { "family": "Mecklenburg", "given": "Matthew" } }, { "id": "Melot-Brent-C", "name": { "family": "Melot", "given": "Brent C." }, "orcid": "0000-0002-7078-8206" }, { "id": "Jho-Young-Dahl", "name": { "family": "Jho", "given": "Young-Dahl" } }, { "id": "Howe-Brandon-M", "name": { "family": "Howe", "given": "Brandon M." } }, { "id": "Mishra-Rohan", "name": { "family": "Mishra", "given": "Rohan" }, "orcid": "0000-0003-1261-0087" }, { "id": "Alatas-Ahmet", "name": { "family": "Alatas", "given": "Ahmet" }, "orcid": "0000-0001-6521-856X" }, { "id": "Winn-Barry", "name": { "family": "Winn", "given": "Barry" } }, { "id": "Manley-Michael-E", "name": { "family": "Manley", "given": "Michael E." }, "orcid": "0000-0003-4053-9986" }, { "id": "Ravichandran-Jayakanth", "name": { "family": "Ravichandran", "given": "Jayakanth" }, "orcid": "0000-0001-5030-9143" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "High frequency atomic tunneling yields ultralow and glass-like thermal conductivity in chalcogenide single crystals", "ispublished": "pub", "full_text_status": "public", "keywords": "Materials for energy and catalysis; Quantum mechanics; Structure of solids and liquids", "note": "\u00a9 The Author(s) 2020. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. \n\nReceived 28 June 2020; Accepted 25 October 2020; Published 27 November 2020. \n\nN.S. and A.J.M. acknowledge the support of the DARPA MATRIX program under Grant No. HR0011-15-2-0039. B.S., Y.J., and A.J.M. acknowledge the support of the GIST-Caltech Research Collaboration in 2018. J.R. and S.N. acknowledge the support from the Air Force Office of Scientific Research under award no. FA9550-16-1-0335 and Army Research Office under award no. W911NF-19-1-0137. Neutron and X-ray scattering research (R.P.H. and M.E.M.) and STEM characterization (A.S.T. and R.M.) are sponsored by the U.S. Department of Energy (DOE), Office of Basic Energy Sciences, Materials Sciences and Engineering Division. J.M.-G. and B.C.M. gratefully acknowledge support from the Office of Naval Research Grant No. N00014-15-1-2411. A.S.T. and R.M. acknowledge support through the National Science Foundation grant DMR-1806147. S.N. acknowledges Link Foundation Energy Fellowship. This research used resources at the Spallation Neutron Source and the Center for Nanophase Materials Sciences, DOE Office of Science User Facility operated by the Oak Ridge National Laboratory, and resources of the Advanced Photon Source, a U.S. DOE Office of Science User Facility operated by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. We thank Dr. Rakesh Singh and Cameron Kopas for performing the RBS experiments. M.E.M. and R.P.H. acknowledge encouraging discussions with Brian Sales. \n\nData availability: The authors declare that the data supporting the findings of this study are available within the paper and its Supplementary Information files. \n\nAuthor Contributions: These authors contributed equally: Bo Sun, Shanyuan Niu, Raphael P. Hermann. \n\nA.J.M. and J.R. conceived the project and supervised the research. B.S. performed TDTR measurements with help from Y.-D.J. on thin film deposition. S.N. grew the crystals and performed structural characterizations and electrical measurements with B.Z. N.S. contributed to the first-principle calculations. K.L.P. and M.E.M. conducted the neutron diffraction measurements. A.S.T., R.M., K.M., B.M.H., and M.M. performed STEM imaging studies. R.H. contributed to single-crystal XRD measurements. J.M.-G. and B.C.M. contributed to heat capacity studies. R.P.H., J.M., A.A., and M.E.M. conducted the inelastic X-ray scattering measurements and analysis. M.E.M. and B.W. conducted the inelastic neutron scattering measurements to identify the tunneling mechanism proposed by R.P.H. All authors discussed the results. B.S., A.J.M., and M.E.M. wrote the manuscript with contributions from all authors. \n\nThe authors declare no competing interests. \n\nPeer review information: Nature Communications thanks Jie Ma, Nuo Yang and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.\n\nPublished - s41467-020-19872-w.pdf
Supplemental Material - 41467_2020_19872_MOESM1_ESM.pdf
", "abstract": "Crystalline solids exhibiting glass-like thermal conductivity have attracted substantial attention both for fundamental interest and applications such as thermoelectrics. In most crystals, the competition of phonon scattering by anharmonic interactions and crystalline imperfections leads to a non-monotonic trend of thermal conductivity with temperature. Defect-free crystals that exhibit the glassy trend of low thermal conductivity with a monotonic increase with temperature are desirable because they are intrinsically thermally insulating while retaining useful properties of perfect crystals. However, this behavior is rare, and its microscopic origin remains unclear. Here, we report the observation of ultralow and glass-like thermal conductivity in a hexagonal perovskite chalcogenide single crystal, BaTiS\u2083, despite its highly symmetric and simple primitive cell. Elastic and inelastic scattering measurements reveal the quantum mechanical origin of this unusual trend. A two-level atomic tunneling system exists in a shallow double-well potential of the Ti atom and is of sufficiently high frequency to scatter heat-carrying phonons up to room temperature. While atomic tunneling has been invoked to explain the low-temperature thermal conductivity of solids for decades, our study establishes the presence of sub-THz frequency tunneling systems even in high-quality, electrically insulating single crystals, leading to anomalous transport properties well above cryogenic temperatures.", "date": "2020-11-27", "date_type": "published", "publication": "Nature Communications", "volume": "11", "number": "1", "publisher": "Nature Publishing Group", "pagerange": "Art. No. 6039", "id_number": "CaltechAUTHORS:20201202-091711333", "issn": "2041-1723", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20201202-091711333", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Defense Advanced Research Projects Agency (DARPA)", "grant_number": "HR0011-15-2-0039" }, { "agency": "GIST-Caltech Research Collaboration" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-16-1-0335" }, { "agency": "Army Research Office (ARO)", "grant_number": "W911NF-19-1-0137" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-06CH11357" }, { "agency": "Office of Naval Research (ONR)", "grant_number": "N00014-15-1-2411" }, { "agency": "NSF", "grant_number": "DMR-1806147" }, { "agency": "Link Foundation" } ] }, "doi": "10.1038/s41467-020-19872-w", "pmcid": "PMC7699621", "primary_object": { "basename": "s41467-020-19872-w.pdf", "url": "https://authors.library.caltech.edu/records/1kpda-78s09/files/s41467-020-19872-w.pdf" }, "related_objects": [ { "basename": "41467_2020_19872_MOESM1_ESM.pdf", "url": "https://authors.library.caltech.edu/records/1kpda-78s09/files/41467_2020_19872_MOESM1_ESM.pdf" } ], "resource_type": "article", "pub_year": "2020", "author_list": "Sun, Bo; Niu, Shanyuan; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/nsv7s-rh875", "eprint_id": 106335, "eprint_status": "archive", "datestamp": "2023-08-20 08:18:35", "lastmod": "2023-10-20 23:21:53", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hua-Chengyun", "name": { "family": "Hua", "given": "Chengyun" }, "orcid": "0000-0003-3587-8342" }, { "id": "Chen-Xiangwen", "name": { "family": "Chen", "given": "Xiangwen" } }, { "id": "Ravichandran-Navaneetha-K", "name": { "family": "Ravichandran", "given": "Navaneetha K." } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Fresnel transmission coefficients for thermal phonons at solid interfaces", "ispublished": "unpub", "full_text_status": "public", "note": "The authors thank J. Carrete and N. Mingo for providing the first-principles calculations for silicon, Prof. Nathan Lewis group for the access to the ellipsometer, and the Kavli Nanoscience Institute (KNI) at Caltech for the availability of critical cleanroom facilities. X. C. thanks Melissa A. Melendes, Matthew H. Sullivan and Carol M. Garland from the KNI for fabrication assistance, and Victoria W. Dix from the Lewis group at Caltech for the help with the ellipsometer measurements. This work was sponsored in part by the National Science Foundation under Grant no. CBET 1254213, and by Boeing under the Boeing-Caltech Strategic Research & Development Relationship Agreement.\n\nSubmitted - 1509.07806.pdf
", "abstract": "Interfaces play an essential role in phonon-mediated heat conduction in solids, impacting applications ranging from thermoelectric waste heat recovery to heat dissipation in electronics. From a microscopic perspective, interfacial phonon transport is described by transmission and reflection coefficients, analogous to the well-known Fresnel coefficients for light. However, these coefficients have never been directly measured, and thermal transport processes at interfaces remain poorly understood despite considerable effort. Here, we report the first measurements of the Fresnel transmission coefficients for thermal phonons at a metal-semiconductor interface using ab-initio phonon transport modeling and a thermal characterization technique, time-domain thermoreflectance. Our measurements show that interfaces act as thermal phonon filters that transmit primarily low frequency phonons, leading to these phonons being the dominant energy carriers across the interface despite the larger density of states of high frequency phonons. Our work realizes the long-standing goal of directly measuring thermal phonon transmission coefficients and demonstrates a general route to study microscopic processes governing interfacial heat conduction.", "date": "2020-10-29", "date_type": "published", "publisher": "arXiv", "id_number": "CaltechAUTHORS:20201028-142023904", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20201028-142023904", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CBET-1254213" }, { "agency": "Boeing-Caltech Strategic Research & Development Relationship Agreement" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.48550/arXiv.1509.07806", "primary_object": { "basename": "1509.07806.pdf", "url": "https://authors.library.caltech.edu/records/nsv7s-rh875/files/1509.07806.pdf" }, "resource_type": "monograph", "pub_year": "2020", "author_list": "Hua, Chengyun; Chen, Xiangwen; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/nxhvr-0n017", "eprint_id": 106328, "eprint_status": "archive", "datestamp": "2023-08-19 08:15:04", "lastmod": "2023-10-20 23:21:25", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lee-S", "name": { "family": "Lee", "given": "S." } }, { "id": "Jeong-H", "name": { "family": "Jeong", "given": "H." } }, { "id": "Lee-H", "name": { "family": "Lee", "given": "H." } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "A. J." }, "orcid": "0000-0002-9671-9540" }, { "id": "Jeon-S-R", "name": { "family": "Jeon", "given": "S.-R." } }, { "id": "Chung-T-H", "name": { "family": "Chung", "given": "T. H." } }, { "id": "Stanton-C-J", "name": { "family": "Stanton", "given": "C. J." } }, { "id": "Jho-Y-D", "name": { "family": "Jho", "given": "Y. D." } } ] }, "title": "Nonlinear Photoelasticity to Explicate Acoustic Dephasing Dynamics", "ispublished": "unpub", "full_text_status": "public", "note": "We thank Oliver B. Wright and Vitalyi Gusev for their insightful comments and suggestions. This work was supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Science, ICT & Future Planning (2018R1A2B6008101).\n\nSubmitted - 1803.02105.pdf
", "abstract": "Detection and controlling of acoustic (AC) phonon phase have been strenuous tasks although such capability is crucial for further manipulating thermal properties. Here, we present a versatile formalism for tracing AC nanowaves with arbitrary strain compositions by incorporating the nonlinear photoelasticity (PE) into ultrafast acoustics where broad AC spectrum encompassing thermally important THz frequency range should be collected far beyond Brillouin frequency. The initial AC phase upon displacive carrier generation could be inherently varied depending on the bipolar AC compositions by implementing externally biased piezoelectric diodes. The importance of adopting nonlinear PE is then manifested from the transient phase shift either abrupt at the point of diffuse surface scattering or gradual during phonon-phonon or phonon-electron scattering events based on which the ratio of nonlinear to linear PE coefficient is experimentally extracted as a function of the detection probe energy, reaching 0.98 slightly below the bandgap. As the probing energy is rather set away from the bandgap, AC phase is completely invariant with any scattering events, exhibiting the conventional trend at Brillouin frequency in linear regime. Under potent influence of nonlinear PE, the AC dephasing time during the propagation are quantified as a function of AC wavepacket size and further correlated with intrinsic and extrinsic AC scattering mechanisms in electron reservoir.", "date": "2020-10-29", "date_type": "published", "publisher": "arXiv", "id_number": "CaltechAUTHORS:20201028-103558286", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20201028-103558286", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "National Research Foundation of Korea", "grant_number": "2018R1A2B6008101" }, { "agency": "Ministry of Science, ICT and Future Planning (Korea)" } ] }, "doi": "10.48550/arXiv.1803.02105", "primary_object": { "basename": "1803.02105.pdf", "url": "https://authors.library.caltech.edu/records/nxhvr-0n017/files/1803.02105.pdf" }, "resource_type": "monograph", "pub_year": "2020", "author_list": "Lee, S.; Jeong, H.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/8nvdp-0nd60", "eprint_id": 106326, "eprint_status": "archive", "datestamp": "2023-08-19 23:29:20", "lastmod": "2023-10-20 23:21:14", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hua-Chengyun", "name": { "family": "Hua", "given": "Chengyun" }, "orcid": "0000-0003-3587-8342" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Quasiballistic Heat Conduction in Transient Grating Spectroscopy", "ispublished": "unpub", "full_text_status": "public", "note": "License: Attribution 3.0 Unported (CC BY 3.0). \n\nThe authors would like to thank Kimberlee Collins and Gang Chen for useful discussions and for providing the PbSe data. This work was sponsored in part by Robert Bosch LLC through Bosch Energy Research Network Grant no. 13.01.CC11, by the National Science Foundation under Grant no. CBET 1254213, and by Boeing under the Boeing-Caltech Strategic Research & Development Relationship Agreement.\n\nSubmitted - 1402.1449.pdf
", "abstract": "Transient grating (TG) spectroscopy is an important experimental technique to measure mean free path (MFP) spectra using observations of quasiballistic heat conduction. To obtain MFP spectra, the measurements must be interpreted within the framework of the frequency-dependent Boltzmann transport equation (BTE), but previous solutions have restricted validity due to simplifying assumptions. Here, we analyze heat conduction in TG using a new analytical solution of the frequency-dependent BTE that accurately describes thermal transport from the diffusive to ballistic regimes. We demonstrate that our result enables a more accurate measurement of MFP spectra and thus will lead to an improved understanding of heat conduction in solids.", "date": "2020-10-29", "date_type": "published", "publisher": "arXiv", "id_number": "CaltechAUTHORS:20201028-102723795", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20201028-102723795", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Bosch Energy Research Network", "grant_number": "13.01.CC11" }, { "agency": "NSF", "grant_number": "CBET-1254213" }, { "agency": "Boeing-Caltech Strategic Research & Development Relationship Agreement" } ] }, "doi": "10.48550/arXiv.1402.1449", "primary_object": { "basename": "1402.1449.pdf", "url": "https://authors.library.caltech.edu/records/8nvdp-0nd60/files/1402.1449.pdf" }, "resource_type": "monograph", "pub_year": "2020", "author_list": "Hua, Chengyun and Minnich, Austin J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/hmp3k-53g92", "eprint_id": 100329, "eprint_status": "archive", "datestamp": "2023-08-19 20:58:12", "lastmod": "2023-10-18 19:51:43", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gao-Yang", "name": { "family": "Gao", "given": "Yang" }, "orcid": "0000-0003-2320-2839" }, { "id": "Sun-Qiming", "name": { "family": "Sun", "given": "Qiming" }, "orcid": "0000-0003-0528-6186" }, { "id": "Yu-Jason-M", "name": { "family": "Yu", "given": "Jason M." }, "orcid": "0000-0002-2270-6798" }, { "id": "Motta-M", "name": { "family": "Motta", "given": "Mario" }, "orcid": "0000-0003-1647-9864" }, { "id": "McClain-J", "name": { "family": "McClain", "given": "James" } }, { "id": "White-A-F", "name": { "family": "White", "given": "Alec F." }, "orcid": "0000-0002-9743-1469" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" }, { "id": "Chan-Garnet-K-L", "name": { "family": "Chan", "given": "Garnet Kin-Lic" }, "orcid": "0000-0001-8009-6038" } ] }, "title": "Electronic structure of bulk manganese oxide and nickel oxide from coupled cluster theory", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2020 American Physical Society. \n\nReceived 13 December 2019; accepted 27 March 2020; published 27 April 2020. \n\nWe thank Z. Cui and T. Zhu for helpful discussions on spectrum analysis. G.K.-L. C. acknowledges support from Grant No. DE-SC0018140. Partial support for Y.G. was from Grant No. DE-SC0019330. A.F.W. was supported by MURI Grant No. FA9550-18-1-0095. J.M.Y. acknowledges support from NSF Grant No. DGE-1745301. Y.G. and A.J.M. acknowledge the support of ONR under Grant No. N00014-18-1-2101.\n\nPublished - PhysRevB.101.165138.pdf
Submitted - 1910.02191.pdf
", "abstract": "We describe the ground- and excited-state electronic structure of bulk MnO and NiO, two prototypical correlated electron materials, using coupled cluster theory with single and double excitations (CCSD). As a corollary, this work also reports an implementation of unrestricted periodic ab initio equation-of-motion CCSD. Starting from a Hartree-Fock reference, we find fundamental gaps of 3.46 and 4.83 eV for MnO and NiO, respectively, for the 16-unit supercell, slightly overestimated compared to experiment, although finite-size scaling suggests that the gap is more severely overestimated in the thermodynamic limit. From the character of the correlated electronic bands we find both MnO and NiO to lie in the intermediate Mott/charge-transfer insulator regime, although NiO appears as a charge transfer insulator when only the fundamental gap is considered. While the lowest quasiparticle excitations are of metal 3d and O 2p character in most of the Brillouin zone, near the \n\u0393 point, the lowest conduction band quasiparticles are of s character. Our study supports the potential of coupled cluster theory to provide high-level many-body insights into correlated solids.", "date": "2020-04-15", "date_type": "published", "publication": "Physical Review B", "volume": "101", "number": "16", "publisher": "American Physical Society", "pagerange": "Art. No. 165138", "id_number": "CaltechAUTHORS:20191217-105833097", "issn": "2469-9950", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191217-105833097", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0018140" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0019330" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-18-1-0095" }, { "agency": "NSF Graduate Research Fellowship", "grant_number": "DGE-1745301" }, { "agency": "Office of Naval Research (ONR)", "grant_number": "N00014-18-1-2101" } ] }, "doi": "10.1103/PhysRevB.101.165138", "primary_object": { "basename": "PhysRevB.101.165138.pdf", "url": "https://authors.library.caltech.edu/records/hmp3k-53g92/files/PhysRevB.101.165138.pdf" }, "related_objects": [ { "basename": "1910.02191.pdf", "url": "https://authors.library.caltech.edu/records/hmp3k-53g92/files/1910.02191.pdf" } ], "resource_type": "article", "pub_year": "2020", "author_list": "Gao, Yang; Sun, Qiming; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/62c2v-knz91", "eprint_id": 97601, "eprint_status": "archive", "datestamp": "2023-08-22 03:44:32", "lastmod": "2023-10-23 16:12:21", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Motta-M", "name": { "family": "Motta", "given": "Mario" }, "orcid": "0000-0003-1647-9864" }, { "id": "Sun-Chong", "name": { "family": "Sun", "given": "Chong" }, "orcid": "0000-0002-8299-9094" }, { "id": "Tan-Adrian-Teck-Keng", "name": { "family": "Tan", "given": "Adrian T. K." } }, { "id": "O'Rourke-M-J", "name": { "family": "O'Rourke", "given": "Matthew J." }, "orcid": "0000-0002-5779-2577" }, { "id": "Ye-Erika", "name": { "family": "Ye", "given": "Erika" } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" }, { "id": "Brand\u00e3o-F-G-S-L", "name": { "family": "Brand\u00e3o", "given": "Fernando G. S. L." }, "orcid": "0000-0003-3866-9378" }, { "id": "Chan-Garnet-K-L", "name": { "family": "Chan", "given": "Garnet Kin-Lic" }, "orcid": "0000-0001-8009-6038" } ] }, "title": "Determining eigenstates and thermal states on a quantum computer using quantum imaginary time evolution", "ispublished": "pub", "full_text_status": "public", "keywords": "Information theory and computation; Quantum information; Quantum simulation", "note": "\u00a9 2019 Springer Nature Limited. \n\nReceived 01 April 2019; Accepted 24 September 2019; Published 11 November 2019. \n\nData availability: The data that support the findings of this study are available from the corresponding authors on reasonable request. \n\nCode availability: The code used to generate the data presented in this study can be publicly accessed on GitHub at https://github.com/mariomotta/QITE.git. \n\nM.M., G.K.-L.C., F.G.S.L.B., A.T.K.T. and A.J.M. were supported by the US NSF via RAISE-TAQS CCF 1839204. M.J.O'R. was supported by an NSF graduate fellowship via grant No. DEG-1745301; the tensor network algorithms were developed with the support of the US DOD via MURI FA9550-18-1-0095. E.Y. was supported by a Google fellowship. C.S. was supported by the US DOE via DE-SC0019374. G.K.-L.C. is a Simons Investigator in Physics and a member of the Simons Collaboration on the Many-Electron Problem. The Rigetti computations were made possible by a generous grant through Rigetti Quantum Cloud Services supported by the CQIA\u2013Rigetti Partnership Program. We thank G. H. Low, J. R. McClean and R. Babbush for discussions, and the Rigetti team for help with the QVM and QPU simulations. \n\nAuthor Contributions: M.M., C.S. and G.K.-L.C. designed the algorithms. F.G.S.L.B. established the mathematical proofs and error estimates. E.Y. and M.J.O'R. performed classical tensor network simulations. M.M., C.S. and A.T.K.T. carried out classical exact emulations. A.T.K.T. and A.J.M. designed and carried out the Rigetti QVM and QPU experiments. All authors contributed to the discussion of results and writing of the manuscript. \n\nThe authors declare no competing interests.\n\nSubmitted - 1901.07653.pdf
", "abstract": "The accurate computation of Hamiltonian ground, excited and thermal states on quantum computers stands to impact many problems in the physical and computer sciences, from quantum simulation to machine learning. Given the challenges posed in constructing large-scale quantum computers, these tasks should be carried out in a resource-efficient way. In this regard, existing techniques based on phase estimation or variational algorithms display potential disadvantages; phase estimation requires deep circuits with ancillae, that are hard to execute reliably without error correction, while variational algorithms, while flexible with respect to circuit depth, entail additional high-dimensional classical optimization. Here, we introduce the quantum imaginary time evolution and quantum Lanczos algorithms, which are analogues of classical algorithms for finding ground and excited states. Compared with their classical counterparts, they require exponentially less space and time per iteration, and can be implemented without deep circuits and ancillae, or high-dimensional optimization. We furthermore discuss quantum imaginary time evolution as a subroutine to generate Gibbs averages through an analogue of minimally entangled typical thermal states. Finally, we demonstrate the potential of these algorithms via an implementation using exact classical emulation as well as through prototype circuits on the Rigetti quantum virtual machine and Aspen-1 quantum processing unit.", "date": "2020-02", "date_type": "published", "publication": "Nature Physics", "volume": "16", "number": "2", "publisher": "Nature Publishing Group", "pagerange": "205-210", "id_number": "CaltechAUTHORS:20190801-134541389", "issn": "1745-2473", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190801-134541389", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CCF-1839204" }, { "agency": "NSF Graduate Research Fellowship", "grant_number": "DGE-1745301" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-18-1-0095" }, { "agency": "Google" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0019374" }, { "agency": "Simons Foundation" }, { "agency": "Rigetti Quantum Cloud Services" }, { "agency": "CQIA-Rigetti Partnership Program" } ] }, "local_group": { "items": [ { "id": "IQIM" } ] }, "doi": "10.1038/s41567-019-0704-4", "primary_object": { "basename": "1901.07653.pdf", "url": "https://authors.library.caltech.edu/records/62c2v-knz91/files/1901.07653.pdf" }, "resource_type": "article", "pub_year": "2020", "author_list": "Motta, Mario; Sun, Chong; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/any73-f1e71", "eprint_id": 98679, "eprint_status": "archive", "datestamp": "2023-08-19 17:43:24", "lastmod": "2023-10-18 17:33:35", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Cheng-Peishi", "name": { "family": "Cheng", "given": "Peishi" }, "orcid": "0000-0002-3513-9972" }, { "id": "Shulumba-Nina", "name": { "family": "Shulumba", "given": "Nina" }, "orcid": "0000-0002-2374-7487" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Thermal transport and phonon focusing in complex molecular crystals: Ab initio study of polythiophene", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2019 American Physical Society. \n\nReceived 17 May 2019; revised manuscript received 31 July 2019; published 17 September 2019. \n\nThis work was supported by the Office of Naval Research under Award No. N00014-18-1-2101. This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation Grant No. ACI-1548562. This work used Comet under XSEDE at the San Diego Supercomputing Center through allocation TG-PHY160029 and the Navy DoD Supercomputing Resource Center (DSRC).\n\nPublished - PhysRevB.100.094306.pdf
", "abstract": "Thermally conductive molecular crystals are of fundamental interest because they are unlike typical complex crystals, which conduct heat poorly owing to their large phonon scattering phase space. While molecular crystals with high thermal conductivity in the range of tens of Wm^(\u22121)K^(\u22121) have been known experimentally for decades, their intrinsic upper limits for thermal conductivity are unclear. Ab initio methods that have been successfully applied to simple crystals have proved difficult to adapt to molecular crystals due to quantum nuclear motion and their complex primitive cells. Here, we report the thermal transport properties of crystalline polythiophene with 28 atoms per primitive cell using an ab initio approach that rigorously includes finite-temperature anharmonicity and quantum nuclear effects. The calculated room temperature thermal conductivity is 198Wm^(\u22121)K^(\u22121) along the chain axis, a high value that arises from exceptional phonon focusing along the chain for both acoustic and optical branches for nearly all wave vectors and despite short lifetimes in the picosecond range. Our finding, along with other recent ab initio studies of polyethylene, suggests that the intrinsic upper bounds for the chain axis thermal conductivity of polymer crystals may exceed 100Wm^(\u22121)K^(\u22121).", "date": "2019-09-01", "date_type": "published", "publication": "Physical Review B", "volume": "100", "number": "9", "publisher": "American Physical Society", "pagerange": "Art. No. 094306", "id_number": "CaltechAUTHORS:20190917-133017527", "issn": "2469-9950", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190917-133017527", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Office of Naval Research (ONR)", "grant_number": "N00014-18-1-2101" }, { "agency": "NSF", "grant_number": "ACI-1548562" } ] }, "doi": "10.1103/physrevb.100.094306", "primary_object": { "basename": "PhysRevB.100.094306.pdf", "url": "https://authors.library.caltech.edu/records/any73-f1e71/files/PhysRevB.100.094306.pdf" }, "resource_type": "article", "pub_year": "2019", "author_list": "Cheng, Peishi; Shulumba, Nina; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/pk8v9-h0f72", "eprint_id": 97801, "eprint_status": "archive", "datestamp": "2023-08-22 02:18:39", "lastmod": "2023-10-18 16:45:17", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Robbins-Andrew-B", "name": { "family": "Robbins", "given": "Andrew B." }, "orcid": "0000-0002-8328-1762" }, { "id": "Drakopoulos-Stavros-X", "name": { "family": "Drakopoulos", "given": "Stavros X." }, "orcid": "0000-0002-6798-0790" }, { "id": "Martin-Fabiani-Ignacio", "name": { "family": "Martin-Fabiani", "given": "Ignacio" }, "orcid": "0000-0002-1977-7659" }, { "id": "Ronca-Sara", "name": { "family": "Ronca", "given": "Sara" }, "orcid": "0000-0003-3434-6352" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Ballistic thermal phonons traversing nanocrystalline domains in oriented polyethylene", "ispublished": "pub", "full_text_status": "public", "keywords": "polymers; polyethylene; thermal conductivity; mean free path; ballistic transport", "note": "\u00a9 2019 National Academy of Sciences. Published under the PNAS license. \n\nEdited by Timothy M. Swager, Massachusetts Institute of Technology, Cambridge, MA, and approved July 10, 2019 (received for review April 6, 2019). PNAS first published August 12, 2019. \n\nA.B.R. and A.J.M. were supported by an Office of Naval Research Young Investigator Award under Grant N00014-15-1-2688. S.R. acknowledges funding from Engineering and Physical Sciences Research Council, Grant EP/K034405/1. We thank Dr. Steven Huband and Dr. Tara Schiller at the University of Warwick X-ray facility for assistance during the SAXS/WAXS measurements and analysis; and Dr. Georgios C. Psarras from the Department of Materials Science, University of Patras, for providing the ZnO nanoparticles. We thank Dr. Giuseppe Forte for providing disentangled UHMWPE. \n\nAuthor contributions: A.B.R., S.R., and A.J.M. designed research; A.B.R., S.X.D., and I.M.-F. performed research; A.B.R., S.X.D., and I.M.-F. analyzed data; and A.B.R. and A.J.M. wrote the paper. \n\nThe authors declare no conflict of interest. \n\nThis article is a PNAS Direct Submission. \n\nData deposition: Wide-angle and small-angle X-ray scattering data have been deposited at the Loughborough University Repository (https://repository.lboro.ac.uk/articles/Wide-angle_X-ray_scattering_data_from_stretched_UHMWPE_samples/9033998 and https://repository.lboro.ac.uk/articles/Small-angle_X-ray_scattering_data_from_stretched_UHMWPE_samples/9009716, respectively). The raw transient grating data from this article have been deposited in CaltechDATA (https://data.caltech.edu/records/1262). \n\nThis article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1905492116/-/DCSupplemental.\n\nPublished - 17163.full.pdf
Supplemental Material - pnas.1905492116.sapp.pdf
", "abstract": "Thermally conductive polymer crystals are of both fundamental and practical interest for their high thermal conductivity that exceeds that of many metals. In particular, polyethylene fibers and oriented films with uniaxial thermal conductivity exceeding 50 W\u22c5m^(-1)\u22c5K^(-1) have been reported recently, stimulating interest into the underlying microscopic thermal transport processes. While ab initio calculations have provided insight into microscopic phonon properties for perfect crystals, such properties of actual samples have remained experimentally inaccessible. Here, we report the direct observation of thermal phonons with mean free paths up to 200 nm in semicrystalline polyethylene films using transient grating spectroscopy. Many of the mean free paths substantially exceed the crystalline domain sizes measured using small-angle X-ray scattering, indicating that thermal phonons propagate ballistically within and across the nanocrystalline domains; those transmitting across domain boundaries contribute nearly one-third of the thermal conductivity. Our work provides a direct determination of thermal phonon propagation lengths in molecular solids, yielding insights into the microscopic origins of their high thermal conductivity.", "date": "2019-08-27", "date_type": "published", "publication": "Proceedings of the National Academy of Sciences of the United States of America", "volume": "116", "number": "35", "publisher": "National Academy of Sciences", "pagerange": "17163-17168", "id_number": "CaltechAUTHORS:20190812-154046597", "issn": "0027-8424", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190812-154046597", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Office of Naval Research (ONR)", "grant_number": "N00014-15-1-2688" }, { "agency": "Engineering and Physical Sciences Research Council (EPSRC)", "grant_number": "EP/K034405/1" } ] }, "doi": "10.1073/pnas.1905492116", "pmcid": "PMC6717268", "primary_object": { "basename": "17163.full.pdf", "url": "https://authors.library.caltech.edu/records/pk8v9-h0f72/files/17163.full.pdf" }, "related_objects": [ { "basename": "pnas.1905492116.sapp.pdf", "url": "https://authors.library.caltech.edu/records/pk8v9-h0f72/files/pnas.1905492116.sapp.pdf" } ], "resource_type": "article", "pub_year": "2019", "author_list": "Robbins, Andrew B.; Drakopoulos, Stavros X.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/2pxnp-6p348", "eprint_id": 98068, "eprint_status": "archive", "datestamp": "2023-08-19 17:22:01", "lastmod": "2023-10-18 17:00:51", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hua-Chengyun", "name": { "family": "Hua", "given": "Chengyun" }, "orcid": "0000-0003-3587-8342" }, { "id": "Lindsay-L", "name": { "family": "Lindsay", "given": "Lucas" } }, { "id": "Chen-Xiangwen", "name": { "family": "Chen", "given": "Xiangwen" } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Generalized Fourier's law for nondiffusive thermal transport: Theory and experiment", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2019 American Physical Society. \n\nReceived 26 February 2019; revised manuscript received 24 June 2019; published 21 August 2019. \n\nC.H. and L.L. acknowledge support from the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the US Department of Energy. A.J.M. acknowledges support from the National Science Foundation under Grant No. CBET CAREER 1254213. This research used resources of the National Energy Research Scientific Computing Center (NERSC), a US Department of Energy Office of Science User Facility operated under Contract No. DE-AC02-05CH11231.\n\nPublished - PhysRevB.100.085203.pdf
", "abstract": "Phonon heat conduction over length scales comparable to their mean free paths is a topic of considerable interest for basic science and thermal management technologies. However, debate exists over the appropriate constitutive law that defines thermal conductivity in the nondiffusive regime. Here, we derive a generalized Fourier's law that links the heat flux and temperature fields, valid from ballistic to diffusive regimes and for general geometries, using the Peierls-Boltzmann transport equation within the relaxation time approximation. This generalized Fourier's law predicts that thermal conductivity not only becomes nonlocal at length scales smaller than phonon mean free paths but also requires the inclusion of an inhomogeneous nonlocal source term that has been previously neglected. We provide evidence for the validity of this generalized Fourier's law through direct comparison with time-domain thermoreflectance measurements in the nondiffusive regime without adjustable parameters. Furthermore, we show that interpreting experimental data without the generalized Fourier's law can lead to inaccurate measurement of thermal transport properties.", "date": "2019-08-15", "date_type": "published", "publication": "Physical Review B", "volume": "100", "number": "8", "publisher": "American Physical Society", "pagerange": "Art. No. 085203", "id_number": "CaltechAUTHORS:20190821-092908240", "issn": "2469-9950", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190821-092908240", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CBET-1254213" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "doi": "10.1103/PhysRevB.100.085203", "primary_object": { "basename": "PhysRevB.100.085203.pdf", "url": "https://authors.library.caltech.edu/records/2pxnp-6p348/files/PhysRevB.100.085203.pdf" }, "resource_type": "article", "pub_year": "2019", "author_list": "Hua, Chengyun; Lindsay, Lucas; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/00ryt-ntc22", "eprint_id": 95955, "eprint_status": "archive", "datestamp": "2023-08-22 01:50:07", "lastmod": "2023-10-20 20:44:54", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Thomas-Nathan-H", "name": { "family": "Thomas", "given": "Nathan H." }, "orcid": "0000-0003-4648-5325" }, { "id": "Sherrott-M-C", "name": { "family": "Sherrott", "given": "Michelle C." }, "orcid": "0000-0002-7503-9714" }, { "id": "Brouillet-J-J", "name": { "family": "Brouillet", "given": "Jeremy" } }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Electronic Modulation of Near-Field Radiative Transfer in Graphene Field Effect Heterostructures", "ispublished": "pub", "full_text_status": "public", "keywords": "Near-field radiative transfer; graphene; electronic modulation; thermal switches", "note": "\u00a9 2019 American Chemical Society. \n\nReceived: March 15, 2019; Revised: May 10, 2019; Published: May 29, 2019. \n\nThis work is part of the Light-Material Interactions in Energy Conversion Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award No. DE-SC0001293. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. 1144469. M.C.S. gratefully acknowledges fellowship support from the Resnick Sustainability Institute. The authors recognize the Kavli NanoScience Institute at Caltech and to thank Dr. Ognjen Ilic for insightful conversation. \n\nAuthor Contributions: N.H.T. and A.J.M. conceived and designed the experiment. N.H.T. fabricated samples and conducted numerical simulations. M.C.S. assisted in design and sample fabrication. J.B. assisted in sample fabrication. N.H.T., H.A.A., and A.J.M. wrote the manuscript. All authors commented and approved the manuscript. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - nl9b01086_si_001.pdf
", "abstract": "Manipulating heat flow in a controllable and reversible manner is a topic of fundamental and practical interest. Numerous approaches to perform thermal switching have been reported, but they typically suffer from various limitations, for instance requiring mechanical modulation of a submicron gap spacing or only operating in a narrow temperature window. Here, we report the experimental modulation of radiative heat flow by electronic gating of a graphene field effect heterostructure without any moving elements. We measure a maximum heat flux modulation of 4 \u00b1 3% and an absolute modulation depth of 24 \u00b1 7 mW m^(\u20132) V^(\u20131) in samples with vacuum gap distances ranging from 1 to 3 \u03bcm. The active area in the samples through which heat is transferred is \u223c1 cm^2, indicating the scalable nature of these structures. A clear experimental path exists to realize switching ratios as large as 100%, laying the foundation for electronic control of near-field thermal radiation using 2D materials.", "date": "2019-06-12", "date_type": "published", "publication": "Nano Letters", "volume": "19", "number": "6", "publisher": "American Chemical Society", "pagerange": "3898-3904", "id_number": "CaltechAUTHORS:20190530-095539038", "issn": "1530-6984", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190530-095539038", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001293" }, { "agency": "NSF Graduate Research Fellowship", "grant_number": "DGE-1144469" }, { "agency": "Resnick Sustainability Institute" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" }, { "id": "Resnick-Sustainability-Institute" } ] }, "doi": "10.1021/acs.nanolett.9b01086", "primary_object": { "basename": "nl9b01086_si_001.pdf", "url": "https://authors.library.caltech.edu/records/00ryt-ntc22/files/nl9b01086_si_001.pdf" }, "resource_type": "article", "pub_year": "2019", "author_list": "Thomas, Nathan H.; Sherrott, Michelle C.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/gd13s-kgq32", "eprint_id": 96026, "eprint_status": "archive", "datestamp": "2023-08-19 16:03:00", "lastmod": "2023-10-20 20:48:55", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Moon-Jaeyun", "name": { "family": "Moon", "given": "Jaeyun" } }, { "id": "Hermann-R-P", "name": { "family": "Hermann", "given": "Rapha\u00ebl P." }, "orcid": "0000-0002-6138-5624" }, { "id": "Manley-M-E", "name": { "family": "Manley", "given": "Michael E." }, "orcid": "0000-0003-4053-9986" }, { "id": "Alatas-A", "name": { "family": "Alatas", "given": "Ahmet" }, "orcid": "0000-0001-6521-856X" }, { "id": "Said-A-H", "name": { "family": "Said", "given": "Ayman H." } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Thermal acoustic excitations with atomic-scale wavelengths in amorphous silicon", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2019 American Physical Society. \n\nReceived 4 February 2019; revised manuscript received 6 May 2019; published 3 June 2019. \n\nThe authors thank Nathan Sangkook Lee for helpful discussions in sample preparations, Dr. J\u00f6rg Neuefeind and Michelle Everett for assistance in data collection at NOMAD, and Dr. Bianca Haberl for helpful discussions. The authors thank Dr. John Budai for assistance in data collection at HERIX-30. This work was supported by a Samsung Scholarship and a Resnick Fellowship from the Resnick Sustainability Institute at Caltech, and the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. A portion of this research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. \n\nThis paper has been co-authored by employees of UT-Battelle, LLC, under Contract No. DE AC0500OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this paper, or allow others to do so, for the United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan. \n\nJ.M. and A.J.M. conceived the project. J.M. synthesized the a-Si samples. J.M., A.A., A.H.S, R.P.H., and M.E.M conducted the IXS experiments and analyzed the results. R.P.H. performed the RDF measurements. J.M. performed molecular dynamics calculations. J.M. and A.J.M. wrote the paper with input from all authors. A.J.M. supervised the project. \n\nThe authors declare no competing interests.\n\nPublished - PhysRevMaterials.3.065601.pdf
Supplemental Material - Supplementaryt.pdf
", "abstract": "The vibrational properties of glasses remain a topic of intense interest due to several unresolved puzzles, including the origin of the Boson peak and the mechanisms of thermal transport. Inelastic scattering measurements have revealed that amorphous solids support collective acoustic excitations with low THz frequencies despite the atomic disorder, but these frequencies are well below most of the thermal vibrational spectrum. Here, we report the observation of acoustic excitations with frequencies up to 10 THz in amorphous silicon. The excitations have atomic-scale wavelengths as short as 6 \u00c5 and exist well into the thermal vibrational frequencies. Simulations indicate that these high-frequency waves are supported due to the high group velocity and monatomic composition of a-Si, suggesting that other glasses with these characteristics may also exhibit such excitations. Our findings demonstrate that a substantial portion of thermal vibrational modes in amorphous materials can still be described as a phonon gas despite the lack of atomic order.", "date": "2019-06", "date_type": "published", "publication": "Physical Review Materials", "volume": "3", "number": "6", "publisher": "American Physical Society (APS)", "pagerange": "Art. No. 065601", "id_number": "CaltechAUTHORS:20190603-091248429", "issn": "2475-9953", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190603-091248429", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Samsung Scholarship" }, { "agency": "Resnick Sustainability Institute" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-06CH11357" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC05-00OR22725" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" } ] }, "doi": "10.1103/physrevmaterials.3.065601", "primary_object": { "basename": "PhysRevMaterials.3.065601.pdf", "url": "https://authors.library.caltech.edu/records/gd13s-kgq32/files/PhysRevMaterials.3.065601.pdf" }, "related_objects": [ { "basename": "Supplementaryt.pdf", "url": "https://authors.library.caltech.edu/records/gd13s-kgq32/files/Supplementaryt.pdf" } ], "resource_type": "article", "pub_year": "2019", "author_list": "Moon, Jaeyun; Hermann, Rapha\u00ebl P.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/99a5q-nhg96", "eprint_id": 95021, "eprint_status": "archive", "datestamp": "2023-08-19 15:31:52", "lastmod": "2023-10-20 18:29:36", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Manley-M-E", "name": { "family": "Manley", "given": "M. E." }, "orcid": "0000-0003-4053-9986" }, { "id": "Hellman-Olle", "name": { "family": "Hellman", "given": "O." }, "orcid": "0000-0002-3453-2975" }, { "id": "Shulumba-N", "name": { "family": "Shulumba", "given": "N." }, "orcid": "0000-0002-2374-7487" }, { "id": "May-A-F", "name": { "family": "May", "given": "A. F." }, "orcid": "0000-0003-0777-8539" }, { "id": "Stonaha-P-J", "name": { "family": "Stonaha", "given": "P. J." } }, { "id": "Lynn-J-W", "name": { "family": "Lynn", "given": "J. W." }, "orcid": "0000-0003-3626-4932" }, { "id": "Garlea-V-O", "name": { "family": "Garlea", "given": "V. O." } }, { "id": "Alatas-A", "name": { "family": "Alatas", "given": "A." }, "orcid": "0000-0001-6521-856X" }, { "id": "Hermann-R-P", "name": { "family": "Hermann", "given": "R. P." }, "orcid": "0000-0002-6138-5624" }, { "id": "Budai-J-D", "name": { "family": "Budai", "given": "J. D." }, "orcid": "0000-0002-7444-1306" }, { "id": "Wang-H", "name": { "family": "Wang", "given": "H." } }, { "id": "Sales-B-C", "name": { "family": "Sales", "given": "B. C." } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "A. J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Intrinsic anharmonic localization in thermoelectric PbSe", "ispublished": "pub", "full_text_status": "public", "note": "This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply 2019.\nThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. \n\nReceived 25 October 2018; Accepted 05 April 2019; Published\n26 April 2019. \n\nData availability: The data that support the findings of this study are available from the corresponding author on request. \n\nThe authors thank D. Bansal for assistance in orienting the PbSe crystal. This work was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division under Contract Number DE-AC05-00OR22725. A portion of this research performed at the Oak Ridge National Laboratory's Spallation Neutron Source was sponsored by the US Department of Energy, Office of Basic Energy Sciences. The authors acknowledge the support of the National Institute of Standards and Technology, US Department of Commerce, in providing the neutron research facilities used in this work. The identification of any commercial product or trade name does not imply endorsement or recommendation by the National Institute of Standards and Technology. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. H. Wang's effort was sponsored by the DOE Energy Efficiency and Renewable Energy, Office of Vehicle Technologies Materials program. N.S. and A.J.M. acknowledge the support of the DARPA MATRIX program under Grant No. HR0011-15-2-0039. This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation Grant No. ACI-1053575. \n\nAuthor Contributions: M.E.M. designed the experiments with theoretical guidance from A.J.M., N.S., and O.H. The triple-axis thermal neutron scattering measurements were performed by M.E.M., P.J.S. and J.W.L. The time-of-flight cold neutron scattering measurements were performed by V.O.G., N.S., and M.E.M. The inelastic x-ray scattering measurements were performed by A.A., M.E.M., R.P.H. and J.D.B. The neutron and x-ray scattering data were analyzed by M.E.M. The ab initio simulations were performed by O.H., N.S., and A.J.M. The single crystal growth and Hall effect measurements were performed by A.F.M. and B.C.S. The thermal diffusivity, Seebeck coefficient, and electrical resistivity measurements were performed by H.W. The manuscript was written by M.E.M. with input from all authors. \n\nThe authors declare no competing interests.\n\nPublished - s41467-019-09921-4.pdf
Supplemental Material - 41467_2019_9921_MOESM1_ESM.pdf
Supplemental Material - 41467_2019_9921_MOESM2_ESM.pdf
", "abstract": "Lead chalcogenides have exceptional thermoelectric properties and intriguing anharmonic lattice dynamics underlying their low thermal conductivities. An ideal material for thermoelectric efficiency is the phonon glass\u2013electron crystal, which drives research on strategies to scatter or localize phonons while minimally disrupting electronic-transport. Anharmonicity can potentially do both, even in perfect crystals, and simulations suggest that PbSe is anharmonic enough to support intrinsic localized modes that halt transport. Here, we experimentally observe high-temperature localization in PbSe using neutron scattering but find that localization is not limited to isolated modes \u2013 zero group velocity develops for a significant section of the transverse optic phonon on heating above a transition in the anharmonic dynamics. Arrest of the optic phonon propagation coincides with unusual sharpening of the longitudinal acoustic mode due to a loss of phase space for scattering. Our study shows how nonlinear physics beyond conventional anharmonic perturbations can fundamentally alter vibrational transport properties.", "date": "2019-04-26", "date_type": "published", "publication": "Nature Communications", "volume": "10", "publisher": "Nature Publishing Group", "pagerange": "Art. No. 1928", "id_number": "CaltechAUTHORS:20190426-102857516", "issn": "2041-1723", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190426-102857516", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC05-00OR22725" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-06CH11357" }, { "agency": "Defense Advanced Research Projects Agency (DARPA)", "grant_number": "HR0011-15-2-0039" }, { "agency": "NSF", "grant_number": "ACI-1053575" } ] }, "doi": "10.1038/s41467-019-09921-4", "pmcid": "PMC6486597", "primary_object": { "basename": "41467_2019_9921_MOESM1_ESM.pdf", "url": "https://authors.library.caltech.edu/records/99a5q-nhg96/files/41467_2019_9921_MOESM1_ESM.pdf" }, "related_objects": [ { "basename": "41467_2019_9921_MOESM2_ESM.pdf", "url": "https://authors.library.caltech.edu/records/99a5q-nhg96/files/41467_2019_9921_MOESM2_ESM.pdf" }, { "basename": "s41467-019-09921-4.pdf", "url": "https://authors.library.caltech.edu/records/99a5q-nhg96/files/s41467-019-09921-4.pdf" } ], "resource_type": "article", "pub_year": "2019", "author_list": "Manley, M. E.; Hellman, O.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/nwjp3-x4086", "eprint_id": 92694, "eprint_status": "archive", "datestamp": "2023-08-19 14:15:20", "lastmod": "2023-10-20 16:19:35", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Ye-Erika", "name": { "family": "Ye", "given": "Erika" } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Ab initio based investigation of thermal transport in superlattices using the Boltzmann equation: Assessing the role of phonon coherence", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2019 Author(s). Published under license by AIP Publishing. \n\nSubmitted: 22 October 2018 \u00b7 Accepted: 15 January 2019 \u00b7 Published Online: 5 February 2019.\n\nPublished - 1.5075481.pdf
", "abstract": "The role of the coherent interference of phonons on thermal transport in artificial materials such as superlattices is of intense interest. Recent experimental studies report a non-monotonic trend in thermal conductivity with interface density which is attributed to band-folding of thermal phonons. Various models have been proposed to interpret these measurements, but most make simplifying assumptions that make definitively attributing the trends to the coherent transport difficult. Here, we investigate thermal transport in superlattices in the incoherent limit using the Boltzmann equation with intrinsic phonon dispersions and lifetimes calculated from first-principles. We find that the Boltzmann equation is unable to predict the non-monotonic behavior of thermal conductivity versus superlattice period, supporting the interpretation of phonon interference in recent experiments.", "date": "2019-02-07", "date_type": "published", "publication": "Journal of Applied Physics", "volume": "125", "number": "5", "publisher": "American Institute of Physics", "pagerange": "Art. No. 055107", "id_number": "CaltechAUTHORS:20190205-142100727", "issn": "0021-8979", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190205-142100727", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1063/1.5075481", "primary_object": { "basename": "1.5075481.pdf", "url": "https://authors.library.caltech.edu/records/nwjp3-x4086/files/1.5075481.pdf" }, "resource_type": "article", "pub_year": "2019", "author_list": "Ye, Erika and Minnich, Austin J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/fj7fe-7ms90", "eprint_id": 95887, "eprint_status": "archive", "datestamp": "2023-08-19 13:19:29", "lastmod": "2023-10-20 20:40:35", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "DeAngelis-F", "name": { "family": "DeAngelis", "given": "Freddy" } }, { "id": "Muraleedharan-M-G", "name": { "family": "Muraleedharan", "given": "Murali Gopal" } }, { "id": "Moon-Jaeyun", "name": { "family": "Moon", "given": "Jaeyun" } }, { "id": "Seyf-H-R", "name": { "family": "Seyf", "given": "Hamid Reza" } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" }, { "id": "McGaughey-A-J-H", "name": { "family": "McGaughey", "given": "Alan J. H." } }, { "id": "Henry-A", "name": { "family": "Henry", "given": "Asegun" } } ] }, "title": "Thermal Transport in Disordered Materials", "ispublished": "pub", "full_text_status": "restricted", "keywords": "Disordered materials, Alloys, Amorphous materials, Phonon, Normal modes", "note": "\u00a9 2018 Taylor & Francis. \n\nReceived 31 Mar 2018, Accepted 20 Aug 2018, Published online: 16 Dec 2018. \n\nThis work was supported by the National Science Foundation [grant number 1554050].", "abstract": "We review the status of research on thermal/phonon transport in disordered materials. The term disordered materials is used here to encompass both structural and compositional disorder. It includes structural deviations ranging from an ideal crystal with disordered arrangements of defects all the way to fully amorphous materials, as well as crystals with impurities up through multi-component random alloys. Both types of disorder affect phonons by breaking the symmetry of an idealized crystal and changing their character/mode shapes. These effects have important implications with regard to phonon\u2013phonon interactions, phonon transport and phonon interactions with other quantum particles, which are being actively investigated. Herein, we synthesize the current theoretical understanding, identify the aspects of the problem that require more work, and pose open questions.", "date": "2018-12-16", "date_type": "published", "publication": "Nanoscale and Microscale Thermophysical Engineering", "volume": "23", "number": "2", "publisher": "Taylor & Francis", "pagerange": "81-116", "id_number": "CaltechAUTHORS:20190529-151740633", "issn": "1556-7265", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190529-151740633", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CBET-1554050" } ] }, "doi": "10.1080/15567265.2018.1519004", "resource_type": "article", "pub_year": "2018", "author_list": "DeAngelis, Freddy; Muraleedharan, Murali Gopal; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/9bkgq-srz38", "eprint_id": 90894, "eprint_status": "archive", "datestamp": "2023-08-22 00:19:12", "lastmod": "2023-10-19 14:59:40", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Jurado-Z", "name": { "family": "Jurado", "given": "Zoila" }, "orcid": "0000-0003-4160-5068" }, { "id": "Kou-Junlong", "name": { "family": "Kou", "given": "Junlong" } }, { "id": "Kamali-S-M", "name": { "family": "Kamali", "given": "Seyedeh Mahsa" }, "orcid": "0000-0002-6968-811X" }, { "id": "Faraon-A", "name": { "family": "Faraon", "given": "Andrei" }, "orcid": "0000-0002-8141-391X" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Wavelength-selective thermal extraction for higher efficiency and power density thermophotovoltaics", "ispublished": "pub", "full_text_status": "public", "keywords": "Thin films; Solar cells; Thermophotovoltaics; Energy conversion; Blackbody; Optical filters", "note": "\u00a9 2018 Published by AIP Publishing. \n\nReceived 25 July 2018; accepted 24 October 2018; published online 13 November 2018. \n\nThis work is part of the \"Light-Material Interactions in Energy Conversion\" Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award No. DE-SC0001293. The authors would also like to recognize the Kavli NanoScience Institute at Caltech and Professor George R. Rossman and Dr. Alireza Ghaffari of Caltech for the use of their facilities for fabrication and testing.\n\nPublished - 1.5049733.pdf
", "abstract": "Thermophotovoltaics have long been of interest as an energy conversion technology but suffer from low power density and low efficiency. Structured emitters designed to alter the emission spectrum and increase the efficiency are not stable at the necessary high emitter temperatures and also reduce the power density. Here, we propose a wavelength-selective thermal extraction device that mitigates these challenges and demonstrate a transfer-printing process needed to fabricate the device. The device consists of a ZnS solid hemisphere with a patterned thin film optical filter that passively increases the far-field radiated flux from an emitter within a wavelength band near the bandgap of a photovoltaic cell. Crucially, the device does not need to be in physical contact with the emitter and thus can be maintained at a lower temperature, circumventing the thermal stability challenge. Our work helps one to address long-standing issues with applications of thermophotovoltaics.", "date": "2018-11-14", "date_type": "published", "publication": "Journal of Applied Physics", "volume": "124", "number": "18", "publisher": "American Institute of Physics", "pagerange": "Art. No. 183105", "id_number": "CaltechAUTHORS:20181114-150804858", "issn": "0021-8979", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181114-150804858", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001293" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1063/1.5049733", "primary_object": { "basename": "1.5049733.pdf", "url": "https://authors.library.caltech.edu/records/9bkgq-srz38/files/1.5049733.pdf" }, "resource_type": "article", "pub_year": "2018", "author_list": "Jurado, Zoila; Kou, Junlong; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/fkeec-1h211", "eprint_id": 91326, "eprint_status": "archive", "datestamp": "2023-08-19 12:27:34", "lastmod": "2023-10-19 22:24:51", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Chen-Xiangwen", "name": { "family": "Chen", "given": "Xiangwen" } }, { "id": "Hua-Chengyun", "name": { "family": "Hua", "given": "Chengyun" }, "orcid": "0000-0003-3587-8342" }, { "id": "Zhang-Hang", "name": { "family": "Zhang", "given": "Hang" } }, { "id": "Ravichandran-Navaneetha-K", "name": { "family": "Ravichandran", "given": "Navaneetha K." } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Quasiballistic Thermal Transport from Nanoscale Heaters and the Role of the Spatial Frequency", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2018 American Physical Society. \n\n(Received 24 August 2017; revised manuscript received 24 May 2018; published 29 November 2018) \n\nThe authors thank Alexei Maznev for valuable comments and discussions; Lucas Lindsay for providing the first-principles calculations for silicon; the Kavli Nanoscience (KNI) at Caltech for the availability of critical cleanroom facilities; Guy A. DeRose for discussions and comments on the nanoline array fabrications; Matt H. Sullivan for assistance on FIB and e-beam lithography processing; Carol M. Carland for TEM assistance; and Bo Sun and Peishi Cheng for proofreading the article. This work was sponsored in part by the National Science Foundation under Grant No. CBET CAREER 1254213 and by Boeing under the Boeing-Caltech Strategic Research & Development Relationship Agreement. H.Z. also gratefully acknowledges the financial support of the CAS Pioneer Hundred Talents Program. \n\nThe experiments, analytical model, and simulations were conceived by A.J.M. The experiments and fabrication were performed by X.C. The simulations were performed by C.H. and N.K.R. H.Z. initialized the nanoline array fabrications. The manuscript was written by X.C. and A.J.M. with comments and input from all authors. X.C. and C.H. contributed equally to this work.\n\nPublished - PhysRevApplied.10.054068.pdf
Supplemental Material - spatial_freq_SI_17_1_Times.pdf
", "abstract": "Quasiballistic heat conduction from nanoscale heat sources of size comparable to phonon mean free paths has recently become of intense interest both scientifically and for its applications. Prior work has established that, in the quasiballistic regime, the apparent thermal properties of materials depend both on intrinsic mechanisms and the characteristics of the applied thermal gradient. However, many aspects of this regime remain poorly understood. Here, we experimentally study the thermal response of crystals to large thermal gradients generated by optical heating of nanoline arrays. Our experiments reveal the key role of the spatial frequencies and Fourier series amplitudes of the heating profile for thermal transport in the quasiballistic regime, in contrast to the conventional picture that focuses on the geometric dimensions of the individual heaters. Our work provides the insight needed to rationally mitigate local hot spots in modern applications by manipulating the spatial frequencies of the heater patterns.", "date": "2018-11", "date_type": "published", "publication": "Physical Review Applied", "volume": "10", "number": "5", "publisher": "American Physical Society", "pagerange": "Art. No. 054068", "id_number": "CaltechAUTHORS:20181129-110052131", "issn": "2331-7019", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181129-110052131", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CBET-1254213" }, { "agency": "Boeing-Caltech Strategic Research & Development Relationship Agreement" }, { "agency": "China 1000-Young Talents Plan" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1103/physrevapplied.10.054068", "primary_object": { "basename": "PhysRevApplied.10.054068.pdf", "url": "https://authors.library.caltech.edu/records/fkeec-1h211/files/PhysRevApplied.10.054068.pdf" }, "related_objects": [ { "basename": "spatial_freq_SI_17_1_Times.pdf", "url": "https://authors.library.caltech.edu/records/fkeec-1h211/files/spatial_freq_SI_17_1_Times.pdf" } ], "resource_type": "article", "pub_year": "2018", "author_list": "Chen, Xiangwen; Hua, Chengyun; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/mza32-q4095", "eprint_id": 90144, "eprint_status": "archive", "datestamp": "2023-08-19 11:42:39", "lastmod": "2023-10-18 23:14:17", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Ravichandran-Navaneetha-K", "name": { "family": "Ravichandran", "given": "Navaneetha K." } }, { "id": "Zhang-Hang", "name": { "family": "Zhang", "given": "Hang" } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Spectrally Resolved Specular Reflections of Thermal Phonons from Atomically Rough Surfaces", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2018 the Author(s). Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. \n\n(Received 22 March 2018; revised manuscript received 13 September 2018; published 5 October 2018) \n\nhis work was supported by the National Science Foundation under Grant No. CBET CAREER 1254213. The authors thank A.\u2009A. Maznev and K.\u2009A. Nelson for fruitful discussions about the TG experiment and L. Lindsay for providing the ab initio phonon properties. N.\u2009K.\u2009R. thanks the Resnick Sustainability Institute at Caltech and the Dow Chemical Company for fellowship support. \n\nA.\u2009J.\u2009M. and N.\u2009K.\u2009R. originated the research. H.\u2009Z. and N.\u2009K.\u2009R. fabricated the silicon membrane samples. N.\u2009K.\u2009R. conducted the TG experiments and performed the BTE and the Bayesian inference calculations. N.\u2009K.\u2009R. performed the TEM imaging with help from Carol Garland at the Kavli Nanoscience Institute at Caltech. N.\u2009K.\u2009R. and A.\u2009J.\u2009M. analyzed the results and prepared the manuscript. All authors studied and commented on the manuscript. \n\nThe authors declare no competing financial interests.\n\nPublished - PhysRevX.8.041004
Supplemental Material - Supplementary_Information.pdf
", "abstract": "The reflection of waves from rough surfaces is a fundamental process that plays a role in diverse fields such as optics, acoustics, and seismology. While a quantitative understanding of the reflection process has long been established for many types of waves, the precise manner in which thermal phonons of specific wavelengths reflect from atomically rough surfaces remains unclear owing to limited control over terahertz-frequency phonon generation and detection. Knowledge of these processes is critical for many applications, however, and is particularly important for recent attempts to create novel materials by coherently interfering thermal phonons. Here, we report measurements of a key property for these efforts, the phonon-wavelength-dependent specularity parameter, which describes the probability of specular reflections of thermal phonons at a surface. Our experiments show evidence of specular surface reflections of terahertz thermal phonons in our samples around room temperature and indicate a sensitivity of these reflections to surface imperfections on the scale of just 2\u20133 atomic planes. Our work demonstrates a general route to probe the microscopic interactions of thermal phonons with surfaces that are typically inaccessible with traditional experiments.", "date": "2018-10", "date_type": "published", "publication": "Physical Review X", "volume": "8", "number": "4", "publisher": "American Physical Society", "pagerange": "Art. No. 041004", "id_number": "CaltechAUTHORS:20181005-141404733", "issn": "2160-3308", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181005-141404733", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CBET-1254213" }, { "agency": "Resnick Sustainability Institute" }, { "agency": "Dow Chemical Company" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" }, { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1103/physrevx.8.041004", "primary_object": { "basename": "PhysRevX.8.041004", "url": "https://authors.library.caltech.edu/records/mza32-q4095/files/PhysRevX.8.041004" }, "related_objects": [ { "basename": "Supplementary_Information.pdf", "url": "https://authors.library.caltech.edu/records/mza32-q4095/files/Supplementary_Information.pdf" } ], "resource_type": "article", "pub_year": "2018", "author_list": "Ravichandran, Navaneetha K.; Zhang, Hang; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/s8f9f-v9t15", "eprint_id": 89581, "eprint_status": "archive", "datestamp": "2023-08-19 11:23:54", "lastmod": "2023-10-18 22:50:39", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kou-Jun-long", "name": { "family": "Kou", "given": "Junlong" }, "orcid": "0000-0002-0481-5149" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Dynamic optical control of near-field radiative transfer", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement. \n\nReceived 26 Mar 2018; revised 4 Jun 2018; accepted 5 Jun 2018; published 24 Jul 2018. \n\nFunding: US Department of Energy, Office of Science, Office of Basic Energy Sciences (DE-SC0001293).\n\nPublished - oe-26-18-A729.pdf
", "abstract": "Dynamic control of radiative heat transfer is of fundamental interest as well as for applications in thermal management and energy conversion. However, realizing high contrast control of heat flow without moving parts and with high temporal frequencies remains a challenge. Here, we propose a thermal modulation scheme based on optical pumping of semiconductors in near-field radiative contact. External photo-excitation of the semiconductor emitters leads to increases in the free carrier concentration that in turn alters the plasma frequency, resulting in modulation of near-field thermal radiation. The temporal frequency of the modulation can reach hundreds of kHz limited only by the recombination lifetime, greatly exceeding the bandwidth of methods based on temperature modulcation. Calculations based on fluctuational electrodynamics show that the heat transfer coefficient between two silicon films can be tuned from near zero to 600 Wm^(\u22122)K^(\u22121) with a gap distance of 100 nm at room temperature.", "date": "2018-09-03", "date_type": "published", "publication": "Optics Express", "volume": "26", "number": "18", "publisher": "Optical Society of America", "pagerange": "A729-A736", "id_number": "CaltechAUTHORS:20180912-135435405", "issn": "1094-4087", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180912-135435405", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001293" } ] }, "collection": "CaltechAUTHORS", "doi": "10.1364/oe.26.00a729", "primary_object": { "basename": "oe-26-18-A729.pdf", "url": "https://authors.library.caltech.edu/records/s8f9f-v9t15/files/oe-26-18-A729.pdf" }, "resource_type": "article", "pub_year": "2018", "author_list": "Kou, Junlong and Minnich, Austin J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/3zt3b-zhb61", "eprint_id": 86655, "eprint_status": "archive", "datestamp": "2023-08-19 11:04:13", "lastmod": "2023-10-18 19:50:05", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Guo-Ruiqiang", "name": { "family": "Guo", "given": "Ruiqiang" }, "orcid": "0000-0002-1585-9980" }, { "id": "Jho-Young-Dahl", "name": { "family": "Jho", "given": "Young-Dahl" } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Coherent control of thermal phonon transport in van der Waals superlattices", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2018 The Royal Society of Chemistry. \n\nThe article was received on 15 Mar 2018, accepted on 07 May 2018 and first published on 21 May 2018. \n\nThis work was supported by the \"GIST-Caltech Research Collaboration\" Project through a grant provided by Gwangju Institute of Science and Technology in 2017 and the DARPA MATRIX program under Grant No. HR0011-15-2-0039. \n\nAuthor contributions: R. G. performed the calculations. All authors contributed to the analysis and discussion of the results. R. G. and A. J. M. wrote the manuscript. \n\nThere are no conflicts to declare.\n\nSupplemental Material - c8nr02150c1_si.pdf
", "abstract": "van der Waals (vdW) heterostructures are a central focus of materials science and condensed matter physics due to the novel physical phenomena and properties obtained by precisely stacking heterogeneous atomically thin layers. vdW heterostructures are expected to allow for the coherent manipulation of THz lattice vibrations and hence heat conduction due to the ability to precisely control chemical composition at the atomic scale, but little work has focused on thermal transport in these materials. Here, we report an ab initio study of thermal transport in vdW superlattices consisting of alternating transition metal dichalcogenide atomic layers. Our calculations show that the lattice vibrational spectrum and scattering rates can be precisely manipulated by the choice of each atomically thin layer, resulting in materials with novel properties such as large thermal anisotropies approaching 200 and ultralow cross-plane thermal conductivities comparable to those of amorphous materials. Our work demonstrates how coherent manipulation of phonons in vdW superlattices can expand the property space beyond that occupied by natural materials and suggests an experimental route to realize these properties.", "date": "2018-08-14", "date_type": "published", "publication": "Nanoscale", "volume": "10", "number": "30", "publisher": "Royal Society of Chemistry", "pagerange": "14432-14440", "id_number": "CaltechAUTHORS:20180529-102016012", "issn": "2040-3364", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180529-102016012", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "GIST-Caltech Research Collaboration" }, { "agency": "Gwangju Institute of Science and Technology" }, { "agency": "Defense Advanced Research Projects Agency (DARPA)", "grant_number": "HR0011-15-2-0039" } ] }, "doi": "10.1039/c8nr02150c", "primary_object": { "basename": "c8nr02150c1_si.pdf", "url": "https://authors.library.caltech.edu/records/3zt3b-zhb61/files/c8nr02150c1_si.pdf" }, "resource_type": "article", "pub_year": "2018", "author_list": "Guo, Ruiqiang; Jho, Young-Dahl; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/0v1br-pjm64", "eprint_id": 87995, "eprint_status": "archive", "datestamp": "2023-08-19 11:00:56", "lastmod": "2023-10-18 21:35:26", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Dou-Nicholas-G", "name": { "family": "Dou", "given": "Nicholas G." }, "orcid": "0000-0001-8199-5588" }, { "id": "Jagt-R-A", "name": { "family": "Jagt", "given": "Robert A." } }, { "id": "Portela-C-M", "name": { "family": "Portela", "given": "Carlos M." }, "orcid": "0000-0002-2649-4235" }, { "id": "Greer-J-R", "name": { "family": "Greer", "given": "Julia R." }, "orcid": "0000-0002-9675-1508" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Ultralow Thermal Conductivity and Mechanical Resilience of Architected Nanolattices", "ispublished": "pub", "full_text_status": "public", "keywords": "Multifunctional materials, octet-truss, 3\u03c9, phonon transport, stiffness, recoverability", "note": "\u00a9 2018 American Chemical Society. \n\nReceived: March 23, 2018; Revised: July 3, 2018; Published: July 19, 2018. \n\nThis work was supported by the Air Force Office of Scientific Research (AFOSR) Multifunctional Materials program under grant no. FA9550-14-1-0266. J.R.G. acknowledges financial support from the Department of Defense (DoD) through the Vannevar Bush Faculty Fellowship, and C.M.P. acknowledges support from the Office of Naval Research (ONR) through grant no. N00014-16-1-2431. The authors thank Lucas R. Meza for useful discussions and fabrication assistance, the Kavli Nanoscience Institute at Caltech for providing clean room facilities and staff support, and Prof. Nathan S. Lewis for access to additional fabrication equipment. \n\nAuthor Contributions: N.G.D. built the 3\u03c9 experiment, conducted the thermal measurements, and developed the thermal model. R.A.J. fabricated samples and assisted with thermal measurements. C.M.P. performed the mechanical measurements. J.R.G. and A.J.M. provided technical guidance and supervision. All authors contributed to writing the paper. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - nl8b01191_si_001.pdf
", "abstract": "Creating materials that simultaneously possess ultralow thermal conductivity, high stiffness, and damage tolerance is challenging because thermal and mechanical properties are coupled in most fully dense and porous solids. Nanolattices can fill this void in the property space because of their hierarchical design and nanoscale features. We report that nanolattices composed of 24- to 182-nm-thick hollow alumina beams in the octet-truss architecture achieved thermal conductivities as low as 2 mW m^(\u20131) K^(\u20131) at room temperature while maintaining specific stiffnesses of 0.3 to 3 MPa kg^(\u20131) m^3 and the ability to recover from large deformations. These nanoarchitected materials possess the same ultralow thermal conductivities as aerogels while attaining specific elastic moduli that are nearly 2 orders of magnitude higher. Our work demonstrates a general route to realizing multifunctional materials that occupy previously unreachable regions within the material property space.", "date": "2018-08-08", "date_type": "published", "publication": "Nano Letters", "volume": "18", "number": "8", "publisher": "American Chemical Society", "pagerange": "4755-4761", "id_number": "CaltechAUTHORS:20180719-105749681", "issn": "1530-6984", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180719-105749681", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-14-1-0266" }, { "agency": "Vannever Bush Faculty Fellowship" }, { "agency": "Office of Naval Research (ONR)", "grant_number": "N00014-16-1-2431" }, { "agency": "National Security Science and Engineering Faculty Fellowship" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1021/acs.nanolett.8b01191", "primary_object": { "basename": "nl8b01191_si_001.pdf", "url": "https://authors.library.caltech.edu/records/0v1br-pjm64/files/nl8b01191_si_001.pdf" }, "resource_type": "article", "pub_year": "2018", "author_list": "Dou, Nicholas G.; Jagt, Robert A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/kqg5x-7ga36", "eprint_id": 86730, "eprint_status": "archive", "datestamp": "2023-08-19 09:15:21", "lastmod": "2023-10-18 19:56:35", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Yang-Lina", "name": { "family": "Yang", "given": "Lina" } }, { "id": "Latour-B", "name": { "family": "Latour", "given": "Benoit" } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Phonon transmission at crystalline-amorphous interfaces studied using mode-resolved atomistic Green's functions", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2018 American Physical Society. \n\nReceived 21 February 2018; revised manuscript received 16 April 2018; published 31 May 2018. \n\nThis work was supported by the DARPA MATRIX program under Award No. HR0011-15-2-0039.\n\nPublished - PhysRevB.97.205306.pdf
", "abstract": "The transmission and reflection processes of THz phonons at solid interfaces are of fundamental interest and of importance to thermal conduction in nanocrystalline solids. The processes are challenging to investigate, however, because typical experiments and many computational approaches do not provide transmission coefficients resolved by phonon mode. Here, we examine the modal transmission and reflection processes of THz phonons across an amorphous Si region connected to two crystalline Si leads, a model interface for those that occur in nanocrystalline solids, using mode-resolved atomistic Green's functions. We find that the interface acts as a low-pass filter, reflecting modes of frequency greater than around 3 THz while transmitting those below this frequency, in agreement with a recent experimental report [C. Hua et al., Phys. Rev. B 95, 205423 (2017)]. Further, we find that these low frequency modes travel nearly unimpeded through the interface, maintaining their wave vectors on each side of the interface. Our work shows that even completely disordered regions may not be effective at reflecting THz phonons, with implications for efforts to alter thermal conductivity in nanocrystalline solids.", "date": "2018-05-15", "date_type": "published", "publication": "Physical Review B", "volume": "97", "number": "20", "publisher": "American Physical Society", "pagerange": "Art. No. 205306", "id_number": "CaltechAUTHORS:20180601-072649107", "issn": "2469-9950", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180601-072649107", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Defense Advanced Research Projects Agency (DARPA)", "grant_number": "HR0011-15-2-0039" } ] }, "doi": "10.1103/PhysRevB.97.205306", "primary_object": { "basename": "PhysRevB.97.205306.pdf", "url": "https://authors.library.caltech.edu/records/kqg5x-7ga36/files/PhysRevB.97.205306.pdf" }, "resource_type": "article", "pub_year": "2018", "author_list": "Yang, Lina; Latour, Benoit; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/t4r8k-v6w44", "eprint_id": 85304, "eprint_status": "archive", "datestamp": "2023-08-19 08:25:34", "lastmod": "2023-10-18 18:04:54", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Ilic-O", "name": { "family": "Ilic", "given": "Ognjen" } }, { "id": "Thomas-Nathan-H", "name": { "family": "Thomas", "given": "Nathan H." }, "orcid": "0000-0003-4648-5325" }, { "id": "Christensen-T", "name": { "family": "Christensen", "given": "Thomas" } }, { "id": "Sherrott-M-C", "name": { "family": "Sherrott", "given": "Michelle C." }, "orcid": "0000-0002-7503-9714" }, { "id": "Solja\u010di\u0107-M", "name": { "family": "Solja\u010di\u0107", "given": "Marin" } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" }, { "id": "Miller-O-D", "name": { "family": "Miller", "given": "Owen D." }, "orcid": "0000-0003-2745-2392" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Active Radiative Thermal Switching with Graphene Plasmon Resonators", "ispublished": "pub", "full_text_status": "public", "keywords": "graphene, thermal radiation, near-field radiative heat transfer, surface plasmon", "note": "\u00a9 2018 American Chemical Society. \n\nReceived: November 20, 2017; Accepted: March 12, 2018;\nPublished: March 12, 2018. \n\nO.I., N.H.T., M.C.S, A.J.M., and H.A.A. were supported as part of the DOE \"Light-Material Interactions in Energy Conversion\" Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences under award no. DE-SC0001293. O.I., M.C.S., and H.A.A. acknowledge support from the Northrop Grumman Corporation through NG Next. M.C.S. acknowledges fellowship support from the Resnick Sustainability Institute. O.D.M. was supported by the Air Force Office of Scientific Research under award no. FA9550-17-1-0093. T.C. was supported by the Danish Council for Independent Research (grant DFFC6108-00667). M.S. was supported as part of the Army Research Office through the Institute for Soldier Nanotechnologies under contract no. W911NF-13-D-0001 (photon management for developing nuclear-TPV and fuel-TPV mm-scale-systems). M.S. was also supported as part of the S3TEC, an Energy Frontier Research Center funded by the US Department of Energy under grant no. DE-SC0001299 (for fundamental photon transport related to solar TPVs and solar-TEs). \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - nn7b08231_si_001.pdf
", "abstract": "We theoretically demonstrate a near-field radiative thermal switch based on thermally excited surface plasmons in graphene resonators. The high tunability of graphene enables substantial modulation of near-field radiative heat transfer, which, when combined with the use of resonant structures, overcomes the intrinsically broadband nature of thermal radiation. In canonical geometries, we use nonlinear optimization to show that stacked graphene sheets offer improved heat conductance contrast between \"ON\" and \"OFF\" switching states and that a >10\u00d7 higher modulation is achieved between isolated graphene resonators than for parallel graphene sheets. In all cases, we find that carrier mobility is a crucial parameter for the performance of a radiative thermal switch. Furthermore, we derive shape-agnostic analytical approximations for the resonant heat transfer that provide general scaling laws and allow for direct comparison between different resonator geometries dominated by a single mode. The presented scheme is relevant for active thermal management and energy harvesting as well as probing excited-state dynamics at the nanoscale.", "date": "2018-03-27", "date_type": "published", "publication": "ACS Nano", "volume": "12", "number": "3", "publisher": "American Chemical Society", "pagerange": "2474-2481", "id_number": "CaltechAUTHORS:20180314-101708544", "issn": "1936-0851", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180314-101708544", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001293" }, { "agency": "Northrop Grumman Corporation" }, { "agency": "Resnick Sustainability Institute" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-17-1-0093" }, { "agency": "Danish Council for Independent Research", "grant_number": "DFFC6108-00667" }, { "agency": "Army Research Office (ARO)", "grant_number": "W911NF-13-D-0001" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001299" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" } ] }, "doi": "10.1021/acsnano.7b08231", "primary_object": { "basename": "nn7b08231_si_001.pdf", "url": "https://authors.library.caltech.edu/records/t4r8k-v6w44/files/nn7b08231_si_001.pdf" }, "resource_type": "article", "pub_year": "2018", "author_list": "Ilic, Ognjen; Thomas, Nathan H.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/zd3qt-x0x34", "eprint_id": 84228, "eprint_status": "archive", "datestamp": "2023-08-19 07:15:28", "lastmod": "2023-10-18 16:00:27", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hua-Chengyun", "name": { "family": "Hua", "given": "Chengyun" }, "orcid": "0000-0003-3587-8342" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Heat dissipation in the quasiballistic regime studied using the Boltzmann equation in the spatial frequency domain", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2018 American Physical Society. \n\nReceived 10 November 2017; revised manuscript received 21 December 2017; published 10 January 2018. \n\nC.H.'s research was sponsored by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U.S. Deparment of Energy.\n\nPublished - PhysRevB.97.014307.pdf
Submitted - 1711.04212.pdf
", "abstract": "Quasiballistic heat conduction, in which some phonons propagate ballistically over a thermal gradient, has recently become of intense interest. Most works report that the thermal resistance associated with nanoscale heat sources is far larger than predicted by Fourier's law; however, recent experiments show that in certain cases the difference is negligible despite the heaters being far smaller than phonon mean-free paths. In this work, we examine how thermal resistance depends on the heater geometry using analytical solutions of the Boltzmann equation. We show that the spatial frequencies of the heater pattern play the key role in setting the thermal resistance rather than any single geometric parameter, and that for many geometries the thermal resistance in the quasiballistic regime is no different than the Fourier prediction. We also demonstrate that the spectral distribution of the heat source also plays a major role in the resulting transport, unlike in the diffusion regime. Our work provides an intuitive link between the heater geometry, spectral heating distribution, and the effective thermal resistance in the quasiballistic regime, a finding that could impact strategies for thermal management in electronics and other applications.", "date": "2018-01-01", "date_type": "published", "publication": "Physical Review B", "volume": "97", "number": "1", "publisher": "American Physical Society", "pagerange": "Art. No. 014307", "id_number": "CaltechAUTHORS:20180110-101836591", "issn": "2469-9950", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180110-101836591", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" } ] }, "doi": "10.1103/PhysRevB.97.014307", "primary_object": { "basename": "1711.04212.pdf", "url": "https://authors.library.caltech.edu/records/zd3qt-x0x34/files/1711.04212.pdf" }, "related_objects": [ { "basename": "PhysRevB.97.014307.pdf", "url": "https://authors.library.caltech.edu/records/zd3qt-x0x34/files/PhysRevB.97.014307.pdf" } ], "resource_type": "article", "pub_year": "2018", "author_list": "Hua, Chengyun and Minnich, Austin J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/6vd04-h9q50", "eprint_id": 79119, "eprint_status": "archive", "datestamp": "2023-08-19 07:13:37", "lastmod": "2023-10-26 14:36:26", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Moon-Jaeyun", "name": { "family": "Moon", "given": "Jaeyun" } }, { "id": "Latour-B", "name": { "family": "Latour", "given": "Benoit" } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Propagating elastic vibrations dominate thermal conduction in amorphous silicon", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2018 American Physical Society. \n\nReceived 26 April 2017; revised manuscript received 15 December 2017; published 10 January 2018. \n\nThis work was supported by the Samsung Scholarship, NSF CAREER Award No. CBET 1254213, and the Resnick Fellowship from the Resnick Sustainability Institute at Caltech.\n\nPublished - PhysRevB.97.024201.pdf
Submitted - 1704.08360.pdf
", "abstract": "The thermal atomic vibrations of amorphous solids can be distinguished by whether they propagate as elastic waves or do not propagate due to lack of atomic periodicity. In \na-Si, prior works concluded that nonpropagating waves are the dominant contributors to heat transport, with propagating waves being restricted to frequencies less than a few THz and scattered by anharmonicity. Here, we present a lattice and molecular dynamics analysis of vibrations in \na-Si that supports a qualitatively different picture in which propagating elastic waves dominate the thermal conduction and are scattered by local fluctuations of elastic modulus rather than anharmonicity. We explicitly demonstrate the propagating nature of waves up to around 10 THz, and further show that pseudoperiodic structures with homogeneous elastic properties exhibit a marked temperature dependence characteristic of anharmonic interactions. Our work suggests that most heat is carried by propagating elastic waves in a-Si and demonstrates that manipulating local elastic modulus variations is a promising route to realize amorphous materials with extreme thermal properties.", "date": "2018-01-01", "date_type": "published", "publication": "Physical Review B", "volume": "97", "number": "2", "publisher": "American Physical Society", "pagerange": "Art. No. 024201", "id_number": "CaltechAUTHORS:20170717-075759713", "issn": "2469-9950", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170717-075759713", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Samsung Scholarship" }, { "agency": "NSF", "grant_number": "CBET-1254213" }, { "agency": "Resnick Sustainability Institute" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" } ] }, "doi": "10.1103/PhysRevB.97.024201", "primary_object": { "basename": "1704.08360.pdf", "url": "https://authors.library.caltech.edu/records/6vd04-h9q50/files/1704.08360.pdf" }, "related_objects": [ { "basename": "PhysRevB.97.024201.pdf", "url": "https://authors.library.caltech.edu/records/6vd04-h9q50/files/PhysRevB.97.024201.pdf" } ], "resource_type": "article", "pub_year": "2018", "author_list": "Moon, Jaeyun; Latour, Benoit; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/atvkd-ejj49", "eprint_id": 82810, "eprint_status": "archive", "datestamp": "2023-08-19 05:57:04", "lastmod": "2023-10-17 22:42:00", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Shulumba-Nina", "name": { "family": "Shulumba", "given": "Nina" }, "orcid": "0000-0002-2374-7487" }, { "id": "Hellman-Olle", "name": { "family": "Hellman", "given": "Olle" }, "orcid": "0000-0002-3453-2975" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Lattice Thermal Conductivity of Polyethylene Molecular Crystals from First-Principles Including Nuclear Quantum Effects", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2017 American Physical Society. \n\nReceived 6 April 2017; revised manuscript received 14 June 2017; published 31 October 2017. \n\nN.\u2009S. and A.\u2009J.\u2009M. acknowledge the support of the DARPA MATRIX program under Grant No. HR0011-15-2-0039 and an ONR Young Investigator Award under Grant No. N00014-15-1-2688. O.\u2009H. acknowledges the support from the Swedish Research Council (VR) Program No. 637-2013-7296. This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation Grant No. ACI-1053575 and the Swedish National Infrastructure for Computing (SNIC) at PDC center (High Performance Computing at the KTH Royal Institute of Technology) and National Supercomputer Center (NSC, Link\u00f6ping University). \n\nN.\u2009S. and O.\u2009H. contributed equally to this work.\n\nPublished - PhysRevLett.119.185901.pdf
", "abstract": "Molecular crystals such as polyethylene are of intense interest as flexible thermal conductors, yet their intrinsic upper limits of thermal conductivity remain unknown. Here, we report a study of the vibrational properties and lattice thermal conductivity of a polyethylene molecular crystal using an ab initio approach that rigorously incorporates nuclear quantum motion and finite temperature effects. We obtain a thermal conductivity along the chain direction of around 160\u2009\u2009W\u2009m^(-1)\u2009K^(-1) at room temperature, providing a firm upper bound for the thermal conductivity of this molecular crystal. Furthermore, we show that the inclusion of quantum nuclear effects significantly impacts the thermal conductivity by altering the phase space for three-phonon scattering. Our computational approach paves the way for ab initio studies and computational material discovery of molecular solids free of any adjustable parameters.", "date": "2017-11-03", "date_type": "published", "publication": "Physical Review Letters", "volume": "119", "number": "18", "publisher": "American Physical Society", "pagerange": "Art. No. 185901", "id_number": "CaltechAUTHORS:20171031-135346052", "issn": "0031-9007", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20171031-135346052", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Defense Advanced Research Projects Agency (DARPA)", "grant_number": "HR0011-15-2-0039" }, { "agency": "Office of Naval Research (ONR)", "grant_number": "N00014-15-1-2688" }, { "agency": "Swedish Research Council", "grant_number": "637-2013-7296" }, { "agency": "NSF", "grant_number": "ACI-1053575" }, { "agency": "KTH Royal Institute of Technology" }, { "agency": "Link\u00f6ping University" } ] }, "doi": "10.1103/PhysRevLett.119.185901", "primary_object": { "basename": "PhysRevLett.119.185901.pdf", "url": "https://authors.library.caltech.edu/records/atvkd-ejj49/files/PhysRevLett.119.185901.pdf" }, "resource_type": "article", "pub_year": "2017", "author_list": "Shulumba, Nina; Hellman, Olle; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/n74aw-vg394", "eprint_id": 81811, "eprint_status": "archive", "datestamp": "2023-08-19 05:01:09", "lastmod": "2023-10-17 21:51:00", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Latour-B", "name": { "family": "Latour", "given": "Benoit" } }, { "id": "Shulumba-N", "name": { "family": "Shulumba", "given": "Nina" }, "orcid": "0000-0002-2374-7487" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Ab initio study of mode-resolved phonon transmission at Si/Ge interfaces using atomistic Green's functions", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2017 American Physical Society. \n\nReceived 27 May 2017; revised manuscript received 9 August 2017; published 25 September 2017. \n\nB.L. and A.J.M. acknowledge the support of the DARPA MATRIX program under Grant No. HR0011-15-2-0039 and Boeing under the Boeing-Caltech Strategic Research & Development Relationship Agreement.\n\nPublished - PhysRevB.96.104310.pdf
", "abstract": "Solid interfaces with exceptionally low or high thermal conductance are of intense scientific and practical interest. However, realizing such interfaces is challenging due to a lack of knowledge of the phonon transmission coefficients between specific modes on each side of the interface and how the coefficients are affected by atomic scale structure. Here, we report an ab initio based study of phonon transmission at Si/Ge interfaces using a recent extension of the atomistic Green's function method that resolves transmission coefficients by mode. These results provide a detailed framework to investigate the precise transmission and reflection processes that lead to thermal resistance and how they depend on phonon frequency as well as incident angle. We find that the transmission and reflection processes can be partly explained with familiar concepts such as conservation of transverse momentum, but we also find that numerous phonons have zero transmission coefficient despite the existence of modes that satisfy transverse momentum conservation. This work provides detailed insights into precisely which phonons transmit or reflect at interfaces, knowledge necessary to design solid interfaces with extreme values of thermal conductance for thermoelectricity and heat management applications.", "date": "2017-09-01", "date_type": "published", "publication": "Physical Review B", "volume": "96", "number": "10", "publisher": "American Physical Society", "pagerange": "Art. No. 104310", "id_number": "CaltechAUTHORS:20170925-111428940", "issn": "2469-9950", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170925-111428940", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Defense Advanced Research Projects Agency (DARPA)", "grant_number": "HR0011-15-2-0039" }, { "agency": "Boeing-Caltech Strategic Research & Development Relationship Agreement" } ] }, "doi": "10.1103/PhysRevB.96.104310", "primary_object": { "basename": "PhysRevB.96.104310.pdf", "url": "https://authors.library.caltech.edu/records/n74aw-vg394/files/PhysRevB.96.104310.pdf" }, "resource_type": "article", "pub_year": "2017", "author_list": "Latour, Benoit; Shulumba, Nina; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/1vy8c-s0q37", "eprint_id": 73817, "eprint_status": "archive", "datestamp": "2023-08-19 04:48:22", "lastmod": "2023-10-24 16:29:40", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Liao-Bolin", "name": { "family": "Liao", "given": "Bolin" }, "orcid": "0000-0002-0898-0803" }, { "id": "Najafi-E", "name": { "family": "Najafi", "given": "Ebrahim" }, "orcid": "0000-0003-3634-9346" }, { "id": "Li-Heng", "name": { "family": "Li", "given": "Heng" } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" }, { "id": "Zewail-A-H", "name": { "family": "Zewail", "given": "Ahmed H." } } ] }, "title": "Photo-excited hot carrier dynamics in hydrogenated amorphous silicon imaged by 4D electron microscopy", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2017 Macmillan Publishers Limited, part of Springer Nature. \n\nReceived 21 October 2016; Accepted 22 May 2017; Published online 03 July 2017. \n\nThe authors thank Y. Zhu for providing the sample and X. Fu for discussions. This work is supported by the National Science Foundation (DMR-0964886) and the Air Force Office of Scientific Research (FA9550-11-1-0055) in the Gordon and Betty Moore Centre for Physical Biology at the California Institute of Technology. B.L. acknowledges financial support from the KNI Prize Postdoctoral Fellowship in Nanoscience at the Kavli Nanoscience Institute of the California Institute of Technology. \n\nAuthor Contributions: B.L. and A.H.Z. conceived the project. B.L., E.N. and H.L. conducted the experiment and analysed the results. B.L. wrote the paper. A.J.M. proofread and commented on the manuscript, and advised on the modelling work. A.H.Z. supervised the research. \n\nThe authors declare no competing financial interests.\n\nSubmitted - 1610.03030.pdf
Supplemental Material - nnano.2017.124-s1.pdf
", "abstract": "Charge carrier dynamics in amorphous semiconductors has been a topic of intense research that has been propelled by modern applications in thin-film solar cells, transistors and optical sensors. Charge transport in these materials differs fundamentally from that in crystalline semiconductors owing to the lack of long-range order and high defect density. Despite the existence of well-established experimental techniques such as photoconductivity time-of-flight and ultrafast optical measurements, many aspects of the dynamics of photo-excited charge carriers in amorphous semiconductors remain poorly understood. Here, we demonstrate direct imaging of carrier dynamics in space and time after photo-excitation in hydrogenated amorphous silicon (a-Si:H) by scanning ultrafast electron microscopy (SUEM). We observe an unexpected regime of fast diffusion immediately after photoexcitation, together with spontaneous electron\u2013hole separation and charge trapping induced by the atomic disorder. Our findings demonstrate the rich dynamics of hot carrier transport in amorphous semiconductors that can be revealed by direct imaging based on SUEM.", "date": "2017-09", "date_type": "published", "publication": "Nature Nanotechnology", "volume": "12", "number": "9", "publisher": "Nature Publishing Group", "pagerange": "871-876", "id_number": "CaltechAUTHORS:20170130-103051262", "issn": "1748-3387", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170130-103051262", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "DMR-0964886" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-11-1-0055" }, { "agency": "Kavli Nanoscience Institute" }, { "agency": "Gordon and Betty Moore Foundation" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1038/NNANO.2017.124", "primary_object": { "basename": "nnano.2017.124-s1.pdf", "url": "https://authors.library.caltech.edu/records/1vy8c-s0q37/files/nnano.2017.124-s1.pdf" }, "related_objects": [ { "basename": "1610.03030.pdf", "url": "https://authors.library.caltech.edu/records/1vy8c-s0q37/files/1610.03030.pdf" } ], "resource_type": "article", "pub_year": "2017", "author_list": "Liao, Bolin; Najafi, Ebrahim; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/rqxqj-yd609", "eprint_id": 80663, "eprint_status": "archive", "datestamp": "2023-08-19 04:20:12", "lastmod": "2023-10-17 17:04:20", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kim-Taeyong", "name": { "family": "Kim", "given": "Taeyong" } }, { "id": "Ding-Ding", "name": { "family": "Ding", "given": "Ding" } }, { "id": "Yim-Jong-Hyuk", "name": { "family": "Yim", "given": "Jong-Hyuk" } }, { "id": "Jho-Young-Dahl", "name": { "family": "Jho", "given": "Young-Dahl" } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Elastic and thermal properties of free-standing molybdenum disulfide membranes measured using ultrafast transient grating spectroscopy", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2017 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).\n\nReceived 25 April 2017; accepted 2 August 2017; published online 21 August 2017. \n\nThis work was supported by the \"GIST-Caltech Research Collaboration\" Project through a grant provided by Gwangju Institute of Science and Technology in 2017. T.K. acknowledges the support by the Jeongsong Cultural Foundation (South Korea). D.D. gratefully acknowledges the support by the Agency for Science, Technology and Research (Singapore). The authors thank Stefan Omelchenko, Dr. Ke Sun, Dr. Hang Zhang, and Dr. Dennis Friedrich for experimental assistance, and Dr. Bo Sun and Andrew B. Robbins for the constructive discussions. The authors also gratefully acknowledge the use of equipment from the Caltech Joint Center for Artificial Photosynthesis (JCAP).\n\nPublished - 1_2E4999225.pdf
", "abstract": "Molybdenum disulfide (MoS_2), a member of transition-metal dichalcogenide family, is of intense interest due to its unique electronic and thermoelectric properties. However, reports of its in-plane thermal conductivity vary due to the difficulty of in-plane thermal conductivity measurements on thin films, and an experimental measurement of the in-plane sound velocity has not been reported. Here, we use time-resolved transient grating spectroscopy to simultaneously measure the in-plane elastic and thermal properties of free-standing MoS_2 membranes at room temperature. We obtain a longitudinal acoustic phonon velocity of 7000 \u00b1 40 m s^(\u22121) and an in-plane thermal conductivity of 74 \u00b1 21 W m^(\u22121)K^(\u22121). Our measurements provide useful insights into the elastic and thermal properties of MoS_2 and demonstrate the capability of transient grating spectroscopy to investigate the in-plane vibrational properties of van der Waals materials that are challenging to characterize with conventional methods.", "date": "2017-08", "date_type": "published", "publication": "APL Materials", "volume": "5", "number": "8", "publisher": "American Institute of Physics", "pagerange": "Art. No. 086105", "id_number": "CaltechAUTHORS:20170822-070843697", "issn": "2166-532X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170822-070843697", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "GIST-Caltech Research Collaboration" }, { "agency": "Jeongsong Cultural Foundation (South Korea)" }, { "agency": "Agency for Science, Technology and Research (A*STAR)" } ] }, "collection": "CaltechAUTHORS", "local_group": { "items": [ { "id": "JCAP", "value": "JCAP" } ] }, "doi": "10.1063/1.4999225", "primary_object": { "basename": "1_2E4999225.pdf", "url": "https://authors.library.caltech.edu/records/rqxqj-yd609/files/1_2E4999225.pdf" }, "resource_type": "article", "pub_year": "2017", "author_list": "Kim, Taeyong; Ding, Ding; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/cfcyv-hme36", "eprint_id": 79082, "eprint_status": "archive", "datestamp": "2023-08-19 04:08:13", "lastmod": "2024-01-31 19:55:20", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Thomas-Nathan-H", "name": { "family": "Thomas", "given": "Nathan H." }, "orcid": "0000-0003-4648-5325" }, { "id": "Chen-Zhen", "name": { "family": "Chen", "given": "Zhen" }, "orcid": "0000-0002-5422-8807" }, { "id": "Fan-Shanhui", "name": { "family": "Fan", "given": "Shanhui" }, "orcid": "0000-0002-0081-9732" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Semiconductor-based Multilayer Selective Solar Absorber for Unconcentrated Solar Thermal Energy Conversion", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2017 The Author(s). This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. \n\nReceived: 04 April 2017; Accepted: 25 May 2017; Published online: 13 July 2017. \n\nThis work is part of the 'Light-Material Interactions in Energy Conversion' Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0001293. The authors thank Junlong Kou for assistance with the vacuum chamber, Prof. George Rossman for FTIR assistance, Carol Garland for the transmission electron microscopy work, and the Molecular Materials Research Center of the Beckman Institute at Caltech for the UV-Vis measurements. The authors also thank Prof. Harry Atwater for helpful discussions. \n\nAuthor Contributions: N.T., Z.C., S.F., and A.M. wrote this manuscript. All authors reviewed the manuscript. \n\nData Availability: The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request. \n\nThe authors declare that they have no competing interests.\n\nPublished - redirect-nature.pdf
Supplemental Material - 41598_2017_5235_MOESM1_ESM.pdf
", "abstract": "Solar thermal energy conversion has attracted substantial renewed interest due to its applications in industrial heating, air conditioning, and electricity generation. Achieving stagnation temperatures exceeding 200\u2009\u00b0C, pertinent to these technologies, with unconcentrated sunlight requires spectrally selective absorbers with exceptionally low emissivity in the thermal wavelength range and high visible absorptivity for the solar spectrum. In this Communication, we report a semiconductor-based multilayer selective absorber that exploits the sharp drop in optical absorption at the bandgap energy to achieve a measured absorptance of 76% at solar wavelengths and a low emittance of approximately 5% at thermal wavelengths. In field tests, we obtain a peak temperature of 225\u2009\u00b0C, comparable to that achieved with state-of-the-art selective surfaces. With straightforward optimization to improve solar absorption, our work shows the potential for unconcentrated solar thermal systems to reach stagnation temperatures exceeding 300\u2009\u00b0C, thereby eliminating the need for solar concentrators for mid-temperature solar applications such as supplying process heat.", "date": "2017-07-13", "date_type": "published", "publication": "Scientific Reports", "volume": "7", "publisher": "Nature Publishing Group", "pagerange": "Art. No. 5362", "id_number": "CaltechAUTHORS:20170713-122926567", "issn": "2045-2322", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170713-122926567", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001293" } ] }, "doi": "10.1038/s41598-017-05235-x", "pmcid": "PMC5509749", "primary_object": { "basename": "redirect-nature.pdf", "url": "https://authors.library.caltech.edu/records/cfcyv-hme36/files/redirect-nature.pdf" }, "related_objects": [ { "basename": "41598_2017_5235_MOESM1_ESM.pdf", "url": "https://authors.library.caltech.edu/records/cfcyv-hme36/files/41598_2017_5235_MOESM1_ESM.pdf" } ], "resource_type": "article", "pub_year": "2017", "author_list": "Thomas, Nathan H.; Chen, Zhen; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/4vyp1-cs229", "eprint_id": 77529, "eprint_status": "archive", "datestamp": "2023-08-19 03:39:00", "lastmod": "2023-10-25 23:08:21", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Liao-Bolin", "name": { "family": "Liao", "given": "Bolin" }, "orcid": "0000-0002-0898-0803" }, { "id": "Zhao-Huan", "name": { "family": "Zhao", "given": "Huan" } }, { "id": "Najafi-E", "name": { "family": "Najafi", "given": "Ebrahim" }, "orcid": "0000-0003-3634-9346" }, { "id": "Yan-Xiaodong", "name": { "family": "Yan", "given": "Xiaodong" } }, { "id": "Tian-He", "name": { "family": "Tian", "given": "He" }, "orcid": "0000-0001-7328-2182" }, { "id": "Tice-J", "name": { "family": "Tice", "given": "Jesse" } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" }, { "id": "Wang-Han-Materials-Science", "name": { "family": "Wang", "given": "Han" } }, { "id": "Zewail-A-H", "name": { "family": "Zewail", "given": "Ahmed H." } } ] }, "title": "Spatial-Temporal Imaging of Anisotropic Photocarrier Dynamics in Black Phosphorus", "ispublished": "pub", "full_text_status": "public", "keywords": "Black Phosphorus, Anisotropy, Hot Carrier Dynamics, Ultrafast\nElectron Microscopy", "note": "\u00a9 2017 American Chemical Society. \n\nReceived: March 1, 2017; Revised: May 10, 2017; Published: May 15, 2017. \n\nThis work is partially supported by the National Science Foundation (DMR-0964886) and the Air Force Office of Scientific Research (FA9550-11-1-0055) in the Gordon and Betty Moore Center for Physical Biology at the California Institute of Technology. The work is also supported by the Army Research Office (W911NF-16-1-0435), the Air Force Office of Scientific Research FATE MURI program (FA9550-15-1-0514), and the Northrop Grumman Institute of Optical Nanomaterials and Nanophotonics (NG-ION2) at University of Southern California. B.L. is grateful for the financial support from the KNI Prize Postdoctoral Fellowship in Nanoscience at the Kavli Nanoscience Institute of California Institute of Technology. \n\nAuthor Contributions: B.L., H.Z. and H.W. conceived the project. H.Z. prepared the BP samples. H.Z. and J.T. performed the Raman characterization. B.L. and E.N. carried out the SUEM measurements. B.L., H.Z., X.Y., H.T., A.J.M., and H.W. analyzed the data. B.L., H.Z., A.J.M., and H.W. wrote the manuscript. A.H.Z. led the development of the SUEM technique and supervised the research effort during the initial stage of the project. B.L. and H.Z. contributed equally. \n\nThe authors declare no competing financial interest.\n\nAccepted Version - acs_2Enanolett_2E7b00897.pdf
Submitted - 1702.05835.pdf
Supplemental Material - nl7b00897_si_001.pdf
", "abstract": "As an emerging single elemental layered material with a low symmetry in-plane crystal lattice, black phosphorus (BP) has attracted significant research interest owing to its unique electronic and optoelectronic properties, including its widely tunable bandgap, polarization-dependent photoresponse and highly anisotropic in-plane charge transport. Despite extensive study of the steady-state charge transport in BP, there has not been direct characterization and visualization of the hot carriers dynamics in BP immediately after photoexcitation, which is crucial to understanding the performance of BP-based optoelectronic devices. Here we use the newly developed scanning ultrafast electron microscopy (SUEM) to directly visualize the motion of photoexcited hot carriers on the surface of BP in both space and time. We observe highly anisotropic in-plane diffusion of hot holes with a 15 times higher diffusivity along the armchair (x-) direction than that along the zigzag (y-) direction. Our results provide direct evidence of anisotropic hot carrier transport in BP and demonstrate the capability of SUEM to resolve ultrafast hot carrier dynamics in layered two-dimensional materials.", "date": "2017-06-14", "date_type": "published", "publication": "Nano Letters", "volume": "17", "number": "6", "publisher": "American Chemical Society", "pagerange": "3675-3680", "id_number": "CaltechAUTHORS:20170517-121356807", "issn": "1530-6984", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170517-121356807", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "DMR-0964886" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-11-1-0055" }, { "agency": "Gordon and Betty Moore Foundation" }, { "agency": "Army Research Office (ARO)", "grant_number": "W911NF-16-1-0435" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-15-1-0514" }, { "agency": "Northrop Grumman Corporation" }, { "agency": "Kavli Nanoscience Institute" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1021/acs.nanolett.7b00897", "primary_object": { "basename": "1702.05835.pdf", "url": "https://authors.library.caltech.edu/records/4vyp1-cs229/files/1702.05835.pdf" }, "related_objects": [ { "basename": "acs_2Enanolett_2E7b00897.pdf", "url": "https://authors.library.caltech.edu/records/4vyp1-cs229/files/acs_2Enanolett_2E7b00897.pdf" }, { "basename": "nl7b00897_si_001.pdf", "url": "https://authors.library.caltech.edu/records/4vyp1-cs229/files/nl7b00897_si_001.pdf" } ], "resource_type": "article", "pub_year": "2017", "author_list": "Liao, Bolin; Zhao, Huan; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/kx49d-hna20", "eprint_id": 63924, "eprint_status": "archive", "datestamp": "2023-08-19 03:07:34", "lastmod": "2023-10-17 18:29:07", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hua-Chengyun", "name": { "family": "Hua", "given": "Chengyun" }, "orcid": "0000-0003-3587-8342" }, { "id": "Chen-Xiangwen", "name": { "family": "Chen", "given": "Xiangwen" } }, { "id": "Ravichandran-Navaneetha-K", "name": { "family": "Ravichandran", "given": "Navaneetha K." } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin" }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Experimental metrology to obtain thermal phonon transmission coefficients at solid interfaces", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2017 American Physical Society. \n\nReceived 23 December 2016; revised manuscript received 17 March 2017; published 17 May 2017. \n\nThe authors thank L. Lindsay, and N. Mingo for providing the first-principles calculations for silicon, Nathan Lewis group for the access to the ellipsometer, and the Kavli Nanoscience Institute (KNI) at Caltech for the availability of critical cleanroom facilities. X. C. thanks Melissa A. Melendes, Matthew H. Sullivan, and Carol M. Garland from the KNI for fabrication assistance, and Victoria W. Dix from the Lewis group at Caltech for the help with the ellipsometer measurements. This work was sponsored in part by the National Science Foundation under Grant No. CBET 1254213, and by Boeing under the Boeing-Caltech Strategic Research & Development Relationship Agreement. \n\nC.H. and X.C. contributed equally to this work.\n\nPublished - PhysRevB.95.205423.pdf
Submitted - 1509.07806v1.pdf
", "abstract": "Interfaces play an essential role in phonon-mediated heat conduction in solids, impacting applications ranging from thermoelectric waste heat recovery to heat dissipation in electronics. From the microscopic perspective, interfacial phonon transport is described by transmission coefficients that link vibrational modes in the materials composing the interface. However, direct experimental determination of these coefficients is challenging because most experiments provide a mode-averaged interface conductance that obscures the microscopic detail. Here, we report a metrology to extract thermal phonon transmission coefficients at solid interfaces using ab initio phonon transport modeling and a thermal characterization technique, time-domain thermoreflectance. In combination with transmission electron microscopy characterization of the interface, our approach allows us to link the atomic structure of an interface to the spectral content of the heat crossing it. Our work provides a useful perspective on the microscopic processes governing interfacial heat conduction.", "date": "2017-05-15", "date_type": "published", "publication": "Physical Review B", "volume": "95", "number": "20", "publisher": "American Physical Society", "pagerange": "Art. No. 205423", "id_number": "CaltechAUTHORS:20160125-101850007", "issn": "2469-9950", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160125-101850007", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CBET-1254213" }, { "agency": "Boeing-Caltech Strategic Research & Development Relationship Agreement" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1103/PhysRevB.95.205423", "primary_object": { "basename": "PhysRevB.95.205423.pdf", "url": "https://authors.library.caltech.edu/records/kx49d-hna20/files/PhysRevB.95.205423.pdf" }, "related_objects": [ { "basename": "1509.07806v1.pdf", "url": "https://authors.library.caltech.edu/records/kx49d-hna20/files/1509.07806v1.pdf" } ], "resource_type": "article", "pub_year": "2017", "author_list": "Hua, Chengyun; Chen, Xiangwen; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/jtmcm-mkq80", "eprint_id": 74143, "eprint_status": "archive", "datestamp": "2023-08-19 02:02:29", "lastmod": "2024-02-09 21:24:05", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kou-Jun-long", "name": { "family": "Kou", "given": "Jun-long" }, "orcid": "0000-0002-0481-5149" }, { "id": "Jurado-Z", "name": { "family": "Jurado", "given": "Zoila" }, "orcid": "0000-0003-4160-5068" }, { "id": "Chen-Zhen-EE", "name": { "family": "Chen", "given": "Zhen" }, "orcid": "0000-0002-5422-8807" }, { "id": "Fan-Shanhui", "name": { "family": "Fan", "given": "Shanhui" } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Daytime radiative cooling using near-black infrared emitters", "ispublished": "pub", "full_text_status": "public", "keywords": "passive radiative cooling, thermal radiation, infrared emitters", "note": "\u00a9 2017 American Chemical Society. \n\nReceived: December 12, 2016. Published: February 3, 2017. \n\nThis work is part of the 'Light-Material Interactions in Energy Conversion' Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0001293. The authors thank Prof. George Rossman for FTIR assistance, the Kavli Nanoscience Institute at Caltech for cleanroom facilities, and the Molecular Materials Research Center of the Beckman Institute at Caltech for UV/vis/NIR measurement.\n\nAccepted Version - acsphotonics_2E6b00991.pdf
", "abstract": "Recent works have demonstrated that daytime radiative cooling under direct sunlight can be achieved using multilayer thin films designed to emit in the infrared atmospheric transparency window while reflecting visible light. Here, we demonstrate that a polymer-coated fused silica mirror, as a near-ideal blackbody in the mid-infrared and near-ideal reflector in the solar spectrum, achieves radiative cooling below ambient air temperature under direct sunlight (8.2 \u00b0C) and at night (8.4 \u00b0C). Its performance exceeds that of a multilayer thin film stack fabricated using vacuum deposition methods by nearly 3 \u00b0C. Furthermore, we estimate the cooler has an average net cooling power of about 127 Wm^(-2) during daytime at ambient temperature even considering the significant influence of external conduction and convection, more than twice that reported previously. Our work demonstrates that abundant materials and straight-forward fabrication can be used to achieve daytime radiative cooling, advancing applications such as dry cooling of thermal power plants.", "date": "2017-03-15", "date_type": "published", "publication": "ACS Photonics", "volume": "4", "number": "3", "publisher": "American Chemical Society", "pagerange": "626-630", "id_number": "CaltechAUTHORS:20170208-075325428", "issn": "2330-4022", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170208-075325428", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001293" } ] }, "collection": "CaltechAUTHORS", "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute", "value": "Kavli Nanoscience Institute" } ] }, "doi": "10.1021/acsphotonics.6b00991", "primary_object": { "basename": "acsphotonics_2E6b00991.pdf", "url": "https://authors.library.caltech.edu/records/jtmcm-mkq80/files/acsphotonics_2E6b00991.pdf" }, "resource_type": "article", "pub_year": "2017", "author_list": "Kou, Jun-long; Jurado, Zoila; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/a9mrs-hpw87", "eprint_id": 75231, "eprint_status": "archive", "datestamp": "2023-08-19 02:01:22", "lastmod": "2023-10-20 23:28:24", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Yang-Lina", "name": { "family": "Yang", "given": "Lina" } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Thermal transport in nanocrystalline Si and SiGe by ab initio based Monte Carlo simulation", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2017 The Authors. This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/ \n\nReceived: 16 December 2016. Accepted: 03 February 2017. Published online: 14 March 2017. \n\nThe authors thank Lucas Lindsay for providing the Si dispersion and phonon-phonon lifetimes, and Bolin Liao and Jiawei Zhou for providing electron-phonon lifetimes. This work was supported by the DARPA MATRIX program under Award Number HR0011-15-2-0039. \n\nAuthor Contributions: Lina Yang and Austin J. Minnich wrote this manuscript. All authors reviewed the manuscript. \n\nThe authors declare no competing financial interests.\n\nPublished - srep44254.pdf
Erratum - srep46771.pdf
", "abstract": "Nanocrystalline thermoelectric materials based on Si have long been of interest because Si is earth-abundant, inexpensive, and non-toxic. However, a poor understanding of phonon grain boundary scattering and its effect on thermal conductivity has impeded efforts to improve the thermoelectric figure of merit. Here, we report an ab-initio based computational study of thermal transport in nanocrystalline Si-based materials using a variance-reduced Monte Carlo method with the full phonon dispersion and intrinsic lifetimes from first-principles as input. By fitting the transmission profile of grain boundaries, we obtain excellent agreement with experimental thermal conductivity of nanocrystalline Si [Wang et al. Nano Letters 11, 2206 (2011)]. Based on these calculations, we examine phonon transport in nanocrystalline SiGe alloys with ab-initio electron-phonon scattering rates. Our calculations show that low energy phonons still transport substantial amounts of heat in these materials, despite scattering by electron-phonon interactions, due to the high transmission of phonons at grain boundaries, and thus improvements in ZT are still possible by disrupting these modes. This work demonstrates the important insights into phonon transport that can be obtained using ab-initio based Monte Carlo simulations in complex nanostructured materials.", "date": "2017-03-14", "date_type": "published", "publication": "Scientific Reports", "volume": "7", "publisher": "Nature Publishing Group", "pagerange": "Art. No. 44254", "id_number": "CaltechAUTHORS:20170320-090609578", "issn": "2045-2322", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170320-090609578", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Defense Advanced Research Projects Agency (DARPA)", "grant_number": "HR0011-15-2-0039" } ] }, "collection": "CaltechAUTHORS", "doi": "10.1038/srep44254", "pmcid": "PMC5349535", "primary_object": { "basename": "srep44254.pdf", "url": "https://authors.library.caltech.edu/records/a9mrs-hpw87/files/srep44254.pdf" }, "related_objects": [ { "basename": "srep46771.pdf", "url": "https://authors.library.caltech.edu/records/a9mrs-hpw87/files/srep46771.pdf" } ], "resource_type": "article", "pub_year": "2017", "author_list": "Yang, Lina and Minnich, Austin J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/jj0e7-sp634", "eprint_id": 71765, "eprint_status": "archive", "datestamp": "2023-08-19 00:56:11", "lastmod": "2023-10-23 17:03:21", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Shulumba-Nina", "name": { "family": "Shulumba", "given": "Nina" }, "orcid": "0000-0002-2374-7487" }, { "id": "Hellman-Olle", "name": { "family": "Hellman", "given": "Olle" }, "orcid": "0000-0002-3453-2975" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Intrinsic localized mode and low thermal conductivity of PbSe", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2017 American Physical Society. \n\nReceived 22 September 2016; published 4 January 2017. \n\nN.S. and A.J.M. acknowledge the support of the DARPA MATRIX program under Grant No. HR0011-15-2-0039. O.H. acknowledges the support from the Swedish Research Council (VR) program 637-2013-7296. This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation Grant No. ACI-1053575 and the Swedish National Infrastructure for Computing (SNIC) at PDC Center (High Performance Computing at the KTH Royal Institute of Technology) and National Supercomputer Centre (NSC) at Link\u00f6ping University.\n\nPublished - PhysRevB.95.014302.pdf
Submitted - 1609.08254v1.pdf
", "abstract": "Lead chalcogenides such as PbS, PbSe, and PbTe are of interest for their exceptional thermoelectric properties and strongly anharmonic lattice dynamics. Although PbTe has received the most attention, PbSe has a lower thermal conductivity and a nonlinear temperature dependence of thermal resistivity despite being stiffer, trends that prior first-principles calculations have not fully reproduced. Here, we use ab initio calculations that explicitly account for strong anharmonicity and a computationally efficient stochastic phase-space sampling scheme to identify the origin of this low thermal conductivity as an anomalously large anharmonic interaction, exceeding in strength that in PbTe, between the transverse optic and longitudinal acoustic branches. The strong anharmonicity is reflected in the striking observation of an intrinsic localized mode that forms in the acoustic frequencies. Our work shows the deep insights into thermal phonons that can be obtained from ab initio calculations that do not rely on perturbations from the ground-state phonon dispersion.", "date": "2017-01-01", "date_type": "published", "publication": "Physical Review B", "volume": "95", "number": "1", "publisher": "American Physical Society", "pagerange": "Art. No. 014302", "id_number": "CaltechAUTHORS:20161107-094104743", "issn": "2469-9950", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161107-094104743", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Defense Advanced Research Projects Agency (DARPA)", "grant_number": "HR0011-15-2-0039" }, { "agency": "Swedish Research Council", "grant_number": "637-2013-7296" }, { "agency": "NSF", "grant_number": "ACI-1053575" } ] }, "collection": "CaltechAUTHORS", "doi": "10.1103/PhysRevB.95.014302", "primary_object": { "basename": "PhysRevB.95.014302.pdf", "url": "https://authors.library.caltech.edu/records/jj0e7-sp634/files/PhysRevB.95.014302.pdf" }, "related_objects": [ { "basename": "1609.08254v1.pdf", "url": "https://authors.library.caltech.edu/records/jj0e7-sp634/files/1609.08254v1.pdf" } ], "resource_type": "article", "pub_year": "2017", "author_list": "Shulumba, Nina; Hellman, Olle; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/p3zqq-q2h94", "eprint_id": 71725, "eprint_status": "archive", "datestamp": "2023-08-20 14:17:43", "lastmod": "2023-10-23 17:01:16", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Moon-Jaeyun", "name": { "family": "Moon", "given": "Jaeyun" }, "orcid": "0000-0003-0128-4108" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Sub-amorphous thermal conductivity in amorphous heterogeneous nanocomposites", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2016 Royal Society of Chemistry. \n\nReceived 27 Sep 2016, Accepted 31 Oct 2016, First published online 31 Oct 2016. \n\nThis work was supported by the Samsung Scholarship, NSF CAREER Award CBET 1254213, and Boeing under Boeing-Caltech Strategic Research and Development Relationship Agreement. This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation grant number ACI-1053575. The authors thank Normand Mousseau for providing the atomic positions from the WWW algorithm, and Andrew Robbins, Benoit Latour, Wei Lv, and Asegun Henry for useful discussions.\n\nPublished - c6ra24053d.pdf
Submitted - 1610.00810.pdf
", "abstract": "Pure amorphous solids are traditionally considered to set the lower bound of thermal conductivity due to their disordered atomic structure that impedes vibrational energy transport. However, the lower limits for thermal conductivity in heterogeneous amorphous solids and the physical mechanisms underlying these limits remain unclear. Here, we use equilibrium molecular dynamics to show that an amorphous SiGe nanocomposite can possess thermal conductivity substantially lower than those of the amorphous Si and Ge constituents. Normal mode analysis indicates that the presence of the Ge inclusion localizes vibrational modes with frequency above the Ge cutoff in the Si host, drastically reducing their ability to transport heat. This observation suggests a general route to achieve exceptionally low thermal conductivity in fully dense solids by restricting the vibrational density of states available for transport in heterogeneous amorphous nanocomposites.", "date": "2016-10-31", "date_type": "published", "publication": "RSC Advances", "volume": "6", "number": "107", "publisher": "Royal Society of Chemistry", "pagerange": "105154-105160", "id_number": "CaltechAUTHORS:20161103-145514802", "issn": "2046-2069", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161103-145514802", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Samsung Scholarship" }, { "agency": "NSF", "grant_number": "CBET-1254213" }, { "agency": "Boeing-Caltech Strategic Research & Development Relationship Agreement" }, { "agency": "NSF", "grant_number": "ACI-1053575" } ] }, "doi": "10.1039/c6ra24053d", "primary_object": { "basename": "1610.00810.pdf", "url": "https://authors.library.caltech.edu/records/p3zqq-q2h94/files/1610.00810.pdf" }, "related_objects": [ { "basename": "c6ra24053d.pdf", "url": "https://authors.library.caltech.edu/records/p3zqq-q2h94/files/c6ra24053d.pdf" } ], "resource_type": "article", "pub_year": "2016", "author_list": "Moon, Jaeyun and Minnich, Austin J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/jr6xd-tzx84", "eprint_id": 70267, "eprint_status": "archive", "datestamp": "2023-08-20 13:45:08", "lastmod": "2023-10-20 22:04:47", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Ding-D", "name": { "family": "Ding", "given": "D." } }, { "id": "Kim-T", "name": { "family": "Kim", "given": "T." } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "A. J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Active Thermal Extraction and Temperature Sensing of Near-field Thermal Radiation", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2016 The Author(s). This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/ \n\nReceived: 26 May 2016; Accepted: 10 August 2016; Published online: 06 September 2016. \n\nThis work is part of the 'Light-Material Interactions in Energy Conversion' Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0001293. D.D. gratefully acknowledges the support by the Agency for Science, Technology and Research (Singapore). T.K. acknowledges the support by the Jeongsong Cultural Foundation (South Korea). A.J.M. acknowledges the support of the Northrop Grumman Corporation.\n\nAuthor Contributions: D.D. conceived the project, D.D. and T.K. conducted the calculations, D.D., T.K. and A.J.M. analyzed the results. D.D. and A.J.M. wrote the paper. All authors reviewed the manuscript. \n\nD. Ding & T. Kim: These authors contributed equally to this work. \n\nThe authors declare no competing financial interests.\n\nPublished - srep32744.pdf
", "abstract": "Recently, we proposed an active thermal extraction (ATX) scheme that enables thermally populated surface phonon polaritons to escape into the far-field. The concept is based on a fluorescence upconversion process that also occurs in laser cooling of solids (LCS). Here, we present a generalized analysis of our scheme using the theoretical framework for LCS. We show that both LCS and ATX can be described with the same mathematical formalism by replacing the electron-phonon coupling parameter in LCS with the electron-photon coupling parameter in ATX. Using this framework, we compare the ideal efficiency and power extracted for the two schemes and examine the parasitic loss mechanisms. This work advances the application of ATX to manipulate near-field thermal radiation for applications such as temperature sensing and active radiative cooling.", "date": "2016-09-06", "date_type": "published", "publication": "Scientific Reports", "volume": "6", "publisher": "Nature Publishing Group", "pagerange": "Art. No. 32744", "id_number": "CaltechAUTHORS:20160912-085005466", "issn": "2045-2322", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160912-085005466", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001293" }, { "agency": "Agency for Science, Technology and Research (A*STAR)" }, { "agency": "Jeongsong Cultural Foundation" }, { "agency": "Northrop Grumman Corporation" } ] }, "doi": "10.1038/srep32744", "pmcid": "PMC5011705", "primary_object": { "basename": "srep32744.pdf", "url": "https://authors.library.caltech.edu/records/jr6xd-tzx84/files/srep32744.pdf" }, "resource_type": "article", "pub_year": "2016", "author_list": "Ding, D.; Kim, T.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/jh21f-wck82", "eprint_id": 67538, "eprint_status": "archive", "datestamp": "2023-08-22 17:38:53", "lastmod": "2023-10-18 21:16:28", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "A. J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Exploring the Extremes of Heat Conduction in Anisotropic Materials", "ispublished": "pub", "full_text_status": "restricted", "keywords": "Phonons; thermal conductivity; anistropic crystals", "note": "\u00a9 2016 Taylor & Francis. \n\nAccepted author version posted online: 30 Mar 2016; Published online: 30 Mar 2016. \n\nThe author thanks Navaneeth Ravichandran and Chengyun Hua for proofreading the article and Ding Ding for assistance with figures. \n\nThis work was supported in part by the National Science Foundation under Grant no. CBET CAREER 1254213, and by Boeing under the Boeing-Caltech Strategic Research & Development Relationship Agreement.", "abstract": "Anisotropic solids possess thermal conductivities ranging from among the highest found in nature, as in the in-plane thermal conductivity of graphite, to the lowest, as in the cross-plane thermal conductivity of disordered layered crystals. Though these extremes of thermal conductivity make anisotropic materials attractive for diverse applications such as thermal management and thermal insulation, the microscopic physics of heat conduction in these materials remain poorly understood. In this review article, we discuss the recent advances in our understanding of thermal phonon transport in anisotropic solids obtained using new theoretical, computational, and experimental tools.", "date": "2016-03-30", "date_type": "published", "publication": "Nanoscale and Microscale Thermophysical Engineering", "volume": "20", "number": "1", "publisher": "Taylor & Francis", "pagerange": "1-21", "id_number": "CaltechAUTHORS:20160601-105013950", "issn": "1556-7265", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160601-105013950", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CBET 1254213" }, { "agency": "Boeing-Caltech Strategic Research & Development Relationship Agreement" } ] }, "doi": "10.1080/15567265.2016.1170080", "resource_type": "article", "pub_year": "2016", "author_list": "Minnich, A. J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/tvmw7-gwc42", "eprint_id": 64639, "eprint_status": "archive", "datestamp": "2023-08-20 10:51:06", "lastmod": "2023-10-17 21:34:12", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Zhang-Hang", "name": { "family": "Zhang", "given": "Hang" } }, { "id": "Chen-Xiangwen", "name": { "family": "Chen", "given": "Xiangwen" } }, { "id": "Jho-Young-Dahl", "name": { "family": "Jho", "given": "Young-Dahl" } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Temperature-Dependent Mean Free Path Spectra of Thermal Phonons Along the c-Axis of Graphite", "ispublished": "pub", "full_text_status": "public", "keywords": "Mean free path, graphite, phonon, cross-plane, thermal conductivity, thickness dependent", "note": "\u00a9 2016 American Chemical Society. \n\nReceived: November 4, 2015; Revised: February 2, 2016; Publication Date (Web): February 3, 2016. \n\nThe authors are grateful to the Kavli Nanoscience Institute at Caltech for the availability of critical cleanroom facilities and to the Lewis Group at Caltech for use of certain facilities. The authors also thank Matthew H. Sullivan for FIB assistance and Carol M. Garland for TEM assistance. This work was supported by a start-up fund from the California Institute of Technology and by the National Science Foundation under CAREER Grant CBET 1254213. H.Z. also gratefully acknowledges the financial support of the CAS Pioneer Hundred Talents Program. \n\nH.Z. and X.C. contributed equally to this work. \n\nThe authors declare no competing financial interest.\n\nSubmitted - 1509.05092v2.pdf
Supplemental Material - nl5b04499_si_001.pdf
", "abstract": "Heat conduction in graphite has been studied for decades because of its exceptionally large thermal anisotropy. While the bulk thermal conductivities along the in-plane and cross-plane directions are well-known, less understood are the microscopic properties of the thermal phonons responsible for heat conduction. In particular, recent experimental and computational works indicate that the average phonon mean free path (MFP) along the c-axis is considerably larger than that estimated by kinetic theory, but the distribution of MFPs remains unknown. Here, we report the first quantitative measurements of c-axis phonon MFP spectra in graphite at a variety of temperatures using time-domain thermoreflectance measurements of graphite flakes with variable thickness. Our results indicate that c-axis phonon MFPs have values of a few hundred nanometers at room temperature and a much narrower distribution than in isotropic crystals. At low temperatures, phonon scattering is dominated by grain boundaries separating crystalline regions of different rotational orientation. Our study provides important new insights into heat transport and phonon scattering mechanisms in graphite and other anisotropic van der Waals solids.", "date": "2016-03-09", "date_type": "published", "publication": "Nano Letters", "volume": "16", "number": "3", "publisher": "American Chemical Society", "pagerange": "1643-1649", "id_number": "CaltechAUTHORS:20160222-135642950", "issn": "1530-6984", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160222-135642950", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Caltech" }, { "agency": "NSF", "grant_number": "CBET 1254213" }, { "agency": "Chinese Academy of Sciences" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1021/acs.nanolett.5b04499", "primary_object": { "basename": "1509.05092v2.pdf", "url": "https://authors.library.caltech.edu/records/tvmw7-gwc42/files/1509.05092v2.pdf" }, "related_objects": [ { "basename": "nl5b04499_si_001.pdf", "url": "https://authors.library.caltech.edu/records/tvmw7-gwc42/files/nl5b04499_si_001.pdf" } ], "resource_type": "article", "pub_year": "2016", "author_list": "Zhang, Hang; Chen, Xiangwen; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/dsr1p-e9b81", "eprint_id": 68803, "eprint_status": "archive", "datestamp": "2023-08-20 10:44:13", "lastmod": "2023-10-20 15:44:46", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kiuru-Tero", "name": { "family": "Kiuru", "given": "Tero" } }, { "id": "Chattopadhyay-G", "name": { "family": "Chattopadhyay", "given": "Goutam" }, "orcid": "0000-0001-7942-5025" }, { "id": "Reck-T-J", "name": { "family": "Reck", "given": "Theodore J." }, "orcid": "0000-0003-1425-0177" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" }, { "id": "Lin-Robert", "name": { "family": "Lin", "given": "Robert" } }, { "id": "Schlecht-E", "name": { "family": "Schlecht", "given": "Erich" } }, { "id": "Siles-J-V", "name": { "family": "Siles", "given": "Jose V." } }, { "id": "Lee-Choonsup", "name": { "family": "Lee", "given": "Choonsup" } }, { "id": "Mehdi-I", "name": { "family": "Mehdi", "given": "Imran" } } ] }, "title": "Thermal Characterization of Substrate Options for High-Power THz Multipliers Over a Broad Temperature Range", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2015 IEEE. \n\nManuscript received September 07, 2015; revised November 30, 2015; accepted December 15, 2015. Date of publication January 12, 2016; date of current version March 21, 2016. \n\nThe work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA under a contract with the National Aeronautics and Space Administration (NASA). \n\nThe authors would like to thank Prof. S. Weinreb, California Institute of Technology (Caltech), for interesting discussions on the topic.", "abstract": "This paper presents thermal characterization results for three high-power THz Schottky frequency multipliers in the temperature range of 20-380 K. All measured multipliers have different substrates: a 5-\u03bcm-thick GaAs membrane, a 40-\u03bcm-thick GaAs substrate, and a 5-\u03bcm-thick GaAs membrane glued to a 20-\u03bcm-thick CVD diamond substrate with polymer bonding agent. The thermal characterization results include such parameters as the maximum average junction temperature of the anodes, device total thermal resistance, and device cooling (or heating) times. The results enable designers to better optimize their devices for the maximum power level and temperature range and system engineers to better predict the overall performance of the system in an environment, where the ambient conditions might change. For example, from the thermal resistance point of view the GaAs membrane on diamond substrate clearly outperforms the device on GaAs membrane alone at room temperature or above. However, perhaps surprisingly, at temperatures below 125 K, the GaAs membrane is on par, or even has lower thermal resistance than the membrane on diamond.", "date": "2016-03", "date_type": "published", "publication": "IEEE Transactions on Terahertz Science and Technology", "volume": "6", "number": "2", "publisher": "IEEE", "pagerange": "328-335", "id_number": "CaltechAUTHORS:20160701-093607086", "issn": "2156-342X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160701-093607086", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Academy of Finland" }, { "agency": "NASA/JPL/Caltech" } ] }, "doi": "10.1109/TTHZ.2015.2511746", "resource_type": "article", "pub_year": "2016", "author_list": "Kiuru, Tero; Chattopadhyay, Goutam; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/mw26j-tss32", "eprint_id": 56991, "eprint_status": "archive", "datestamp": "2023-08-20 10:18:27", "lastmod": "2023-10-23 16:12:53", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Ding-D", "name": { "family": "Ding", "given": "D." } }, { "id": "Kim-T", "name": { "family": "Kim", "given": "T." } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "A. J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Active Thermal Extraction of Near-field Thermal Radiation", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2016 American Physical Society. \n\nReceived 2 April 2015; revised manuscript received 13 January 2016; published 2 February 2016. \n\nThis work is part of the \"Light-Material Interactions in Energy Conversion\" Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award No. DE-SC0001293. D.D. gratefully acknowledges the support by the Agency for Science, Technology and Research (Singapore). T.K. acknowledges the support by the Jeongsong Cultural Foundation (South Korea). A.J.M. acknowledges the support of the Northrop Grumman Corporation.\n\nPublished - PhysRevB.93.081402.pdf
Submitted - 1504.01851v1.pdf
Supplemental Material - Supplement_v7.pdf
", "abstract": "Radiative heat transport between materials supporting surface-phonon polaritons is greatly enhanced when the materials are placed at subwavelength separation as a result of the contribution of near-field surface modes. However, the enhancement is limited to small separations due to the evanescent decay of the surface waves. In this work, we propose and numerically demonstrate an active scheme to extract these modes to the far field. Our approach exploits the monochromatic nature of near-field thermal radiation to drive a transition in a laser gain medium, which, when coupled with external optical pumping, allows the resonant surface mode to be emitted into the far field. Our study demonstrates an approach to manipulate thermal radiation that could find applications in thermal management.", "date": "2016-02-15", "date_type": "published", "publication": "Physical Review B", "volume": "93", "number": "8", "publisher": "American Physical Society", "pagerange": "Art. No. 081402", "id_number": "CaltechAUTHORS:20150427-085451201", "issn": "1098-0121", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150427-085451201", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001293" }, { "agency": "Agency for Science, Technology and Research (A*STAR)" }, { "agency": "Jeongsong Cultural Foundation" }, { "agency": "Northrop Grumman Corporation" } ] }, "doi": "10.1103/PhysRevB.93.081402", "primary_object": { "basename": "1504.01851v1.pdf", "url": "https://authors.library.caltech.edu/records/mw26j-tss32/files/1504.01851v1.pdf" }, "related_objects": [ { "basename": "PhysRevB.93.081402.pdf", "url": "https://authors.library.caltech.edu/records/mw26j-tss32/files/PhysRevB.93.081402.pdf" }, { "basename": "Supplement_v7.pdf", "url": "https://authors.library.caltech.edu/records/mw26j-tss32/files/Supplement_v7.pdf" } ], "resource_type": "article", "pub_year": "2016", "author_list": "Ding, D.; Kim, T.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/yns46-c8p28", "eprint_id": 64284, "eprint_status": "archive", "datestamp": "2023-08-20 09:56:36", "lastmod": "2023-10-17 19:39:15", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Ravichandran-Navaneetha-K", "name": { "family": "Ravichandran", "given": "Navaneetha K." } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Role of thermalizing and nonthermalizing walls in phonon heat conduction along thin films", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2016 American Physical Society. \n\nReceived 5 November 2015; revised manuscript received 31 December 2015; published 28 January 2016.\n\nN.K.R. would like to thank the Resnick Sustainability Institute at Caltech and the Dow Chemical Company for fellowship support. A.J.M. was supported by the National Science Foundation under Grant No. CBET CAREER 1254213.\n\nPublished - PhysRevB.93.035314.pdf
Submitted - 1511.03312v1.pdf
Supplemental Material - Supplementary_Material_V1.pdf
", "abstract": "Phonon boundary scattering is typically treated using the Fuchs-Sondheimer theory, which assumes that phonons are thermalized to the local temperature at the boundary. However, whether such a thermalization process actually occurs and its effect on thermal transport remains unclear. Here we examine thermal transport along thin films with both thermalizing and nonthermalizing walls by solving the spectral Boltzmann transport equation for steady state and transient transport. We find that in steady state, the thermal transport is governed by the Fuchs-Sondheimer theory and is insensitive to whether the boundaries are thermalizing or not. In contrast, under transient conditions, the thermal decay rates are significantly different for thermalizing and nonthermalizing walls. We also show that, for transient transport, the thermalizing boundary condition is unphysical due to violation of heat flux conservation at the boundaries. Our results provide insights into the boundary scattering process of thermal phonons over a range of heating length scales that are useful for interpreting thermal measurements on nanostructures.", "date": "2016-01-15", "date_type": "published", "publication": "Physical Review B", "volume": "93", "number": "3", "publisher": "American Physical Society", "pagerange": "Art. No. 035314", "id_number": "CaltechAUTHORS:20160205-142512254", "issn": "2469-9950", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160205-142512254", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Resnick Sustainability Institute" }, { "agency": "Dow Chemical Company" }, { "agency": "NSF", "grant_number": "CBET 1254213" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" } ] }, "doi": "10.1103/PhysRevB.93.035314", "primary_object": { "basename": "1511.03312v1.pdf", "url": "https://authors.library.caltech.edu/records/yns46-c8p28/files/1511.03312v1.pdf" }, "related_objects": [ { "basename": "PhysRevB.93.035314.pdf", "url": "https://authors.library.caltech.edu/records/yns46-c8p28/files/PhysRevB.93.035314.pdf" }, { "basename": "Supplementary_Material_V1.pdf", "url": "https://authors.library.caltech.edu/records/yns46-c8p28/files/Supplementary_Material_V1.pdf" } ], "resource_type": "article", "pub_year": "2016", "author_list": "Ravichandran, Navaneetha K. and Minnich, Austin J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/0v919-7mw47", "eprint_id": 63760, "eprint_status": "archive", "datestamp": "2023-08-20 09:51:48", "lastmod": "2023-10-17 16:06:30", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Dou-N-G", "name": { "family": "Dou", "given": "Nicholas G." } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Heat conduction in multifunctional nanotrusses studied using Boltzmann transport equation", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2016 AIP Publishing LLC. \n\nReceived 16 October 2015. Accepted 15 December 2015. Published online 04 January 2016. \n\nThis work was supported by the Air Force Office of Scientific Research (AFOSR) Multifunctional Materials program under Grant No. FA9550-14-1-0266. The authors thank Lucas Meza and Julia R. Greer for useful discussions.\n\nPublished - 1.4939266.pdf
Submitted - 1510.05715v1.pdf
", "abstract": "Materials that possess low density, low thermal conductivity, and high stiffness are desirable for engineering applications, but most materials cannot realize these properties simultaneously due to the coupling between them. Nanotrusses, which consist of hollow nanoscale beams architected into a periodic truss structure, can potentially break these couplings due to their lattice architecture and nanoscale features. In this work, we study heat conduction in the exact nanotruss geometry by solving the frequency-dependent Boltzmann transport equation using a variance-reduced Monte Carlo algorithm. We show that their thermal conductivity can be described with only two parameters, solid fraction and wall thickness. Our simulations predict that nanotrusses can realize unique combinations of mechanical and thermal properties that are challenging to achieve in typical materials.", "date": "2016-01-04", "date_type": "published", "publication": "Applied Physics Letters", "volume": "108", "number": "1", "publisher": "American Institute of Physics", "pagerange": "Art. No. 011902", "id_number": "CaltechAUTHORS:20160119-100115926", "issn": "0003-6951", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160119-100115926", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-14-1-0266" } ] }, "doi": "10.1063/1.4939266", "primary_object": { "basename": "1.4939266.pdf", "url": "https://authors.library.caltech.edu/records/0v919-7mw47/files/1.4939266.pdf" }, "related_objects": [ { "basename": "1510.05715v1.pdf", "url": "https://authors.library.caltech.edu/records/0v919-7mw47/files/1510.05715v1.pdf" } ], "resource_type": "article", "pub_year": "2016", "author_list": "Dou, Nicholas G. and Minnich, Austin J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/5zkdm-ys691", "eprint_id": 62488, "eprint_status": "archive", "datestamp": "2023-08-20 09:06:11", "lastmod": "2023-10-25 17:11:45", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Robbins-A-B", "name": { "family": "Robbins", "given": "Andrew B." }, "orcid": "0000-0002-8328-1762" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Crystalline polymers with exceptionally low thermal conductivity studied using molecular dynamics", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 AIP Publishing LLC. \n\nReceived 14 September 2015; accepted 9 November 2015; published online 19 November 2015. \n\nThis work was supported by an ONR Young Investigator Award under Grant No. N00014-15-1-2688 and by startup funds from Caltech. The authors thank Professor William A. Goddard and members of his group for assistance with the LAMMPS software.\n\nPublished - 1.4936195.pdf
Submitted - 1509.04365v1.pdf
", "abstract": "Semi-crystalline polymers have been shown to have greatly increased thermal conductivity compared to amorphous bulk polymers due to effective heat conduction along the covalent bonds of the backbone. However, the mechanisms governing the intrinsic thermal conductivity of polymers remain largely unexplored as thermal transport has been studied in relatively few polymers. Here, we use molecular dynamics simulations to study heat transport in polynorbornene, a polymer that can be synthesized in semi-crystalline form using solution processing. We find that even perfectly crystalline polynorbornene has an exceptionally low thermal conductivity near the amorphous limit due to extremely strong anharmonic scattering. Our calculations show that this scattering is sufficiently strong to prevent the formation of propagating phonons, with heat being instead carried by non-propagating, delocalized vibrational modes known as diffusons. Our results demonstrate a mechanism for achieving intrinsically low thermal conductivity even in crystalline polymers that may be useful for organic thermoelectrics.", "date": "2015-11-16", "date_type": "published", "publication": "Applied Physics Letters", "volume": "107", "number": "20", "publisher": "American Institute of Physics", "pagerange": "Art. No. 201908", "id_number": "CaltechAUTHORS:20151201-094003344", "issn": "0003-6951", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151201-094003344", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Office of Naval Research (ONR)", "grant_number": "N00014-15-1-2688" }, { "agency": "Caltech" } ] }, "doi": "10.1063/1.4936195", "primary_object": { "basename": "1.4936195.pdf", "url": "https://authors.library.caltech.edu/records/5zkdm-ys691/files/1.4936195.pdf" }, "related_objects": [ { "basename": "1509.04365v1.pdf", "url": "https://authors.library.caltech.edu/records/5zkdm-ys691/files/1509.04365v1.pdf" } ], "resource_type": "article", "pub_year": "2015", "author_list": "Robbins, Andrew B. and Minnich, Austin J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/czvd0-et252", "eprint_id": 61980, "eprint_status": "archive", "datestamp": "2023-08-20 09:00:36", "lastmod": "2023-10-25 16:07:17", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "A. J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Thermal phonon boundary scattering in anisotropic thin films", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 AIP Publishing LLC.\n\nReceived 3 August 2015; accepted 23 October 2015; published online 3 November 2015.\n\nThe author thanks Lucas Lindsay for providing the\ngraphite dispersion and for useful discussions. This work was\nsponsored in part by the National Science Foundation under\nGrant No. CBET CAREER 1254213 and by Boeing under\nthe Boeing-Caltech Strategic Research & Development\nRelationship Agreement.\n\nPublished - 1.4935160.pdf
Submitted - 1508.00611v1.pdf
", "abstract": "Boundary scattering of thermal phonons in thin solid films is typically analyzed using Fuchs-Sondheimer theory, which provides a simple equation to calculate the reduction of thermal conductivity as a function of the film thickness. However, this widely used equation is not applicable to highly anisotropic solids like graphite because it assumes the phonon dispersion is isotropic. Here, we derive a generalization of the Fuchs-Sondheimer equation for solids with arbitrary dispersion relations and examine its predictions for graphite. We find that the isotropic equation vastly overestimates the boundary scattering that occurs in thin graphite films due to the highly anisotropic group velocity, and that graphite can maintain its high in-plane thermal conductivity even in thin films with thicknesses as small as 10\u2009nm.", "date": "2015-11-02", "date_type": "published", "publication": "Applied Physics Letters", "volume": "107", "number": "18", "publisher": "American Institute of Physics", "pagerange": "Art. No. 183106", "id_number": "CaltechAUTHORS:20151109-092635206", "issn": "0003-6951", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151109-092635206", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CBET 1254213" }, { "agency": "Boeing Company Strategic Research and Development Relationship" } ] }, "doi": "10.1063/1.4935160", "primary_object": { "basename": "1.4935160.pdf", "url": "https://authors.library.caltech.edu/records/czvd0-et252/files/1.4935160.pdf" }, "related_objects": [ { "basename": "1508.00611v1.pdf", "url": "https://authors.library.caltech.edu/records/czvd0-et252/files/1508.00611v1.pdf" } ], "resource_type": "article", "pub_year": "2015", "author_list": "Minnich, A. J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/teckn-mvm71", "eprint_id": 60060, "eprint_status": "archive", "datestamp": "2023-08-20 07:45:16", "lastmod": "2023-10-24 14:51:14", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "A. J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Multidimensional quasiballistic thermal transport in transient grating spectroscopy", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 American Physical Society.\n\nReceived 5 June 2015; Revised manuscript received 14 July 2015; Published 13 August 2015.\n\nThe author thanks J. Carrete and N. Mingo for providing the\nfirst-principles data for Si. This work was sponsored, in part, by the National Science Foundation under Grant No. CBET CAREER 1254213 and by Boeing under the Boeing-Caltech\nStrategic Research & Development Relationship Agreement.\n\nPublished - PhysRevB.92.085203.pdf
Submitted - 1506.03149v1.pdf
", "abstract": "Transient grating spectroscopy has emerged as a useful technique to study thermal phonon transport because of its ability to perform thermal measurements over length scales comparable to phonon mean free path (MFPs). Although several prior works have performed theoretical studies of quasiballistic heat conduction in transient grating, the analysis methods are either restricted to one spatial dimension or require phenomenological fitting parameters. Here, we analyze quasiballistic transport in a two-dimensional transient grating experiment in which heat conduction can occur both in and cross plane using an analytic Green's function of the Boltzmann equation we recently reported that is free of fitting parameters. We demonstrate a method by which phonon MFPs can be extracted from these measurements, thereby extending the MFP spectroscopy technique using transient grating to opaque bulk materials.", "date": "2015-08-13", "date_type": "published", "publication": "Physical Review B", "volume": "92", "number": "8", "publisher": "American Physical Society", "pagerange": "Art. No. 085203", "id_number": "CaltechAUTHORS:20150903-152955651", "issn": "1098-0121", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150903-152955651", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF CBET CAREER", "grant_number": "1254213" }, { "agency": "Boeing-Caltech Strategic Research & Development Relationship Agreement" } ] }, "doi": "10.1103/PhysRevB.92.085203", "primary_object": { "basename": "1506.03149v1.pdf", "url": "https://authors.library.caltech.edu/records/teckn-mvm71/files/1506.03149v1.pdf" }, "related_objects": [ { "basename": "PhysRevB.92.085203.pdf", "url": "https://authors.library.caltech.edu/records/teckn-mvm71/files/PhysRevB.92.085203.pdf" } ], "resource_type": "article", "pub_year": "2015", "author_list": "Minnich, A. J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/jr9h8-8qx46", "eprint_id": 60250, "eprint_status": "archive", "datestamp": "2023-08-20 07:31:52", "lastmod": "2023-10-24 15:29:46", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin" }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Engineering the thermal phonon spectrum for thermoelectric energy conversion", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2015 American Chemical Society.", "abstract": "The efficiency of thermoelec. (TE) devices depends on materials with low thermal cond., among other\nproperties, but thermal phonons are sufficiently poorly understood that achieving this low thermal cond.\nremains challenging. Recent works have demonstrated that the thermal phonons responsible for heat\nconduction possess a broad mean free path spectrum, yet this spectrum remains unknown for most materials\nand is often approximated using av. values. In this talk, I will describe our efforts to directly measure and\nengineer the thermal phonon spectrum using computation and expt. Exptl., I will describe our efforts to\ndirectly measure the phonon mean free path spectrum using a new exptl. technique. Computationally, I will\ndemonstrate the importance of considering the size distribution of nanostructures to achieve the min. thermal\ncond. in solids.", "date": "2015-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20150915-092249967", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150915-092249967", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2015", "author_list": "Minnich, Austin" }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/66wxg-rax30", "eprint_id": 56533, "eprint_status": "archive", "datestamp": "2023-08-20 07:25:05", "lastmod": "2023-10-23 15:32:03", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hu-Yongjie", "name": { "family": "Hu", "given": "Yongjie" } }, { "id": "Zeng-Lingping", "name": { "family": "Zeng", "given": "Lingping" } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" }, { "id": "Dresselhaus-M-S", "name": { "family": "Dresselhaus", "given": "Mildred S." } }, { "id": "Chen-Gang", "name": { "family": "Chen", "given": "Gang" } } ] }, "title": "Spectral mapping of thermal conductivity through nanoscale ballistic transport", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 Macmillan Publishers Limited. \n\nReceived 05 April 2014; Accepted 23 April 2015; Published online 01 June 2015. \n\nThe authors thank J. Garg for providing DFT data on Si_(0.992)Ge_(0.008), and D. Broido, N.G. Hadjiconstantinou, A. Marconnet, J.K. Tong, J-P. Peraud, W. Dai, A. Maznev, K. Nelson, J. Cuffe, M. Luckyanova and K. Collins for discussions. This material is based on work supported as part of the 'Solid State Solar-Thermal Energy Conversion Center (S3TEC)', an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences (grant no. DE-SC0001299/DE-FG02-09ER46577). Y.H. is partially supported by the Battelle/MIT Fellowship. \n\nContributions: Y.H. and G.C. developed the concept. Y.H. prepared the samples and performed the experiments. L.Z. performed the Monte Carlo simulation. Y.H. performed the numerical calculations on convex optimizations. All authors discussed the results and commented on the manuscript. G.C. directed the research.\n\nCompeting financial interests: The authors declare no competing financial interests.\n\nSupplemental Material - nnano.2015.109-s1.pdf
", "abstract": "Controlling thermal properties is central to many applications, such as thermoelectric energy conversion and the thermal management of integrated circuits. Progress has been made over the past decade by structuring materials at different length scales, but a clear relationship between structure size and thermal properties remains to be established. The main challenge comes from the unknown intrinsic spectral distribution of energy among heat carriers. Here, we experimentally measure this spectral distribution by probing quasi-ballistic transport near nanostructured heaters down to 30\u2005nm using ultrafast optical spectroscopy. Our approach allows us to quantify up to 95% of the total spectral contribution to thermal conductivity from all phonon modes. The measurement agrees well with multiscale and first-principles-based simulations. We further demonstrate the direct construction of mean free path distributions. Our results provide a new fundamental understanding of thermal transport and will enable materials design in a rational way to achieve high performance.", "date": "2015-08", "date_type": "published", "publication": "Nature Nanotechnology", "volume": "10", "number": "8", "publisher": "Nature Publishing Group", "pagerange": "701-706", "id_number": "CaltechAUTHORS:20150409-123218459", "issn": "1748-3387", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150409-123218459", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001299" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-09ER46577" }, { "agency": "Battelle/MIT Fellowship" } ] }, "doi": "10.1038/nnano.2015.109", "primary_object": { "basename": "nnano.2015.109-s1.pdf", "url": "https://authors.library.caltech.edu/records/66wxg-rax30/files/nnano.2015.109-s1.pdf" }, "resource_type": "article", "pub_year": "2015", "author_list": "Hu, Yongjie; Zeng, Lingping; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ch9nq-z3m82", "eprint_id": 57400, "eprint_status": "archive", "datestamp": "2023-08-20 06:12:50", "lastmod": "2023-10-23 17:21:23", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hua-Chengyun", "name": { "family": "Hua", "given": "Chengyun" }, "orcid": "0000-0003-3587-8342" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Semi-analytical solution to the frequency-dependent Boltzmann transport equation for cross-plane heat conduction in thin films", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 AIP Publishing LLC.\n\nReceived 4 March 2015; accepted 18 April 2015; published online 5 May 2015.\n\nThis work was sponsored in part by the National Science Foundation under Grant No. CBET CAREER 1254213, and by Boeing under the Boeing-Caltech Strategic Research and Development Relationship Agreement.\n\nPublished - 1.4919432.pdf
", "abstract": "Cross-plane heat transport in thin films with thicknesses comparable to the phonon mean free paths is of both fundamental and practical interest for applications such as light-emitting diodes and quantum well lasers. However, physical insight is difficult to obtain for the cross-plane geometry due to the challenge of solving the Boltzmann equation in a finite domain. Here, we present a semi-analytical series expansion method to solve the transient, frequency-dependent Boltzmann transport equation that is valid from the diffusive to ballistic transport regimes and rigorously includes the frequency-dependence of phonon properties. Further, our method is more than three orders of magnitude faster than prior numerical methods and provides a simple analytical expression for the thermal conductivity as a function of film thickness. Our result enables a straightforward physical understanding of cross-plane heat conduction in thin films.", "date": "2015-05-07", "date_type": "published", "publication": "Journal of Applied Physics", "volume": "117", "number": "17", "publisher": "American Institute of Physics", "pagerange": "Art. No. 175306", "id_number": "CaltechAUTHORS:20150511-075225662", "issn": "0021-8979", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150511-075225662", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CBET 1254213" }, { "agency": "Boeing-Caltech Strategic Research & Development Relationship Agreement" } ] }, "doi": "10.1063/1.4919432", "primary_object": { "basename": "1.4919432.pdf", "url": "https://authors.library.caltech.edu/records/ch9nq-z3m82/files/1.4919432.pdf" }, "resource_type": "article", "pub_year": "2015", "author_list": "Hua, Chengyun and Minnich, Austin J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/x0cj2-sh952", "eprint_id": 56997, "eprint_status": "archive", "datestamp": "2023-08-20 05:45:48", "lastmod": "2023-10-23 16:56:24", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Ding-Ding", "name": { "family": "Ding", "given": "Ding" } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Selective Radiative Heating of Nanostructures Using Hyperbolic Metamaterials", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 Optical Society of America.\n\nReceived 14 Nov 2014; revised 29 Jan 2015; accepted 5 Feb 2015; published 9 Mar 2015.\n\nThe authors thank J. D. Caldwell for useful discussions. This work is part of the 'Light-Material Interactions in Energy Conversion' Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0001293. D.D. gratefully acknowledges fellowship support from the Agency for Science, Technology and Research (Singapore).\n\nPublished - oe-23-7-A299.pdf
Submitted - 1412.4906v1.pdf
", "abstract": "Hyperbolic metamaterials (HMM) are of great interest due to their ability to break the diffraction limit for imaging and enhance near-field radiative heat transfer. Here we demonstrate that an annular, transparent HMM enables selective heating of a sub-wavelength plasmonic nanowire by controlling the angular mode number of a plasmonic resonance. A nanowire emitter, surrounded by an HMM, appears dark to incoming radiation from an adjacent nanowire emitter unless the second emitter is surrounded by an identical lens such that the wavelength and angular mode of the plasmonic resonance match. Our result can find applications in radiative thermal management.", "date": "2015-04-06", "date_type": "published", "publication": "Optics Express", "volume": "23", "number": "7", "publisher": "Optical Society of America", "pagerange": "A299-A308", "id_number": "CaltechAUTHORS:20150427-095909805", "issn": "1094-4087", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150427-095909805", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001293" }, { "agency": "Agency for Science, Technology and Research (A*STAR)" } ] }, "doi": "10.1364/OE.23.00A299", "primary_object": { "basename": "1412.4906v1.pdf", "url": "https://authors.library.caltech.edu/records/x0cj2-sh952/files/1412.4906v1.pdf" }, "related_objects": [ { "basename": "oe-23-7-A299.pdf", "url": "https://authors.library.caltech.edu/records/x0cj2-sh952/files/oe-23-7-A299.pdf" } ], "resource_type": "article", "pub_year": "2015", "author_list": "Ding, Ding and Minnich, Austin J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/qtzd5-4y603", "eprint_id": 51529, "eprint_status": "archive", "datestamp": "2023-08-20 05:24:36", "lastmod": "2023-10-18 16:48:53", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Zhang-Hang", "name": { "family": "Zhang", "given": "Hang" } }, { "id": "Hua-Chengyun", "name": { "family": "Hua", "given": "Chengyun" }, "orcid": "0000-0003-3587-8342" }, { "id": "Ding-Ding", "name": { "family": "Ding", "given": "Ding" } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Length Dependent Thermal Conductivity Measurements Yield Phonon Mean Free Path Spectra in Nanostructures", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 Macmillan Publishers Limited. This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder in order to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/ \n\nReceived 29 October 2014; Accepted 19 February 2015; Published 13 March 2015. \n\nThis work was supported by a start-up fund from the California Institute of Technology and by the National Science Foundation under CAREER Grant CBET 1254213. \n\nAuthor Contributions: H.Z., C.H. and D.D. performed simulations and calculations. H.Z. and A.M. analyzed data. H.Z., A.M., C.H. and D.D. discussed the result. H.Z. and A.M. wrote the main manuscript text.\n\nPublished - srep09121.pdf
Submitted - 1410.6233v1.pdf
", "abstract": "Thermal conductivity measurements over variable lengths on nanostructures such as nanowires provide important information about the mean free paths (MFPs) of the phonons responsible for heat conduction. However, nearly all of these measurements have been interpreted using an average MFP even though phonons in many crystals possess a broad MFP spectrum. Here, we present a reconstruction method to obtain MFP spectra of nanostructures from variable-length thermal conductivity measurements. Using this method, we investigate recently reported length-dependent thermal conductivity measurements on SiGe alloy nanowires and suspended graphene ribbons. We find that the recent measurements on graphene imply that 70% of the heat in graphene is carried by phonons with MFPs longer than 1 micron.", "date": "2015-03-13", "date_type": "published", "publication": "Scientific Reports", "volume": "5", "number": "3", "publisher": "Nature Publishing Group", "pagerange": "Art. No. 9121", "id_number": "CaltechAUTHORS:20141110-143729775", "issn": "2045-2322", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141110-143729775", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Caltech" }, { "agency": "NSF", "grant_number": "CBET-1254213" } ] }, "doi": "10.1038/srep09121", "pmcid": "PMC4357850", "primary_object": { "basename": "1410.6233v1.pdf", "url": "https://authors.library.caltech.edu/records/qtzd5-4y603/files/1410.6233v1.pdf" }, "related_objects": [ { "basename": "srep09121.pdf", "url": "https://authors.library.caltech.edu/records/qtzd5-4y603/files/srep09121.pdf" } ], "resource_type": "article", "pub_year": "2015", "author_list": "Zhang, Hang; Hua, Chengyun; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/pkt04-3tp50", "eprint_id": 45134, "eprint_status": "archive", "datestamp": "2023-08-20 05:22:33", "lastmod": "2023-10-26 17:35:11", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Zhang-Hang", "name": { "family": "Zhang", "given": "Hang" } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "The best nanoparticle size distribution for minimum thermal conductivity", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 Macmillan Publishers Limited.\nThis work is licensed under a Creative Commons Attribution 4.0 International\nLicense. The images or other third party material in this article are included in the\narticle's Creative Commons license, unless indicated otherwise in the credit line; if\nthe material is not included under the Creative Commons license, users will need\nto obtain permission from the license holder in order to reproduce the material. To\nview a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.\n\nReceived\n29 October 2014;\nAccepted\n13 February 2015;\nPublished\n11 March 2015.\n\nThis work was supported by a start-up fund from the California Institute of Technology and\nby the National Science Foundation under CAREER Grant CBET 1254213.\n\nAuthor contributions:\nA.M. conceived this project. H.Z. designed the algorithm and performed calculations. H.Z.\nand A.M. analyzed the data. H.Z. and A.M. discussed the result. H.Z. and A.M. wrote the\nmanuscript.\n\nPublished - srep08995.pdf
Submitted - 1404.1438v1.pdf
", "abstract": "Which sizes of nanoparticles embedded in a crystalline solid yield the lowest thermal conductivity? Nanoparticles have long been demonstrated to reduce the thermal conductivity of crystals by scattering phonons, but most previous works assumed the nanoparticles to have a single size. Here, we use optimization methods to show that the best nanoparticle size distribution to scatter the broad thermal phonon spectrum is not a similarly broad distribution but rather several discrete peaks at well-chosen nanoparticle radii. For SiGe, the best size distribution yields a thermal conductivity below that of amorphous silicon. Further, we demonstrate that a simplified distribution yields nearly the same low thermal conductivity and can be readily fabricated. Our work provides important insights into how to manipulate the full spectrum of phonons and will guide the design of more efficient thermoelectric materials.", "date": "2015-03-11", "date_type": "published", "publication": "Scientific Reports", "volume": "5", "publisher": "Nature Publishing Group", "pagerange": "Art. No. 8995", "id_number": "CaltechAUTHORS:20140423-092709245", "issn": "2045-2322", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140423-092709245", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Caltech" }, { "agency": "NSF", "grant_number": "CBET-1254213" } ] }, "doi": "10.1038/srep08995", "pmcid": "PMC4355732", "primary_object": { "basename": "1404.1438v1.pdf", "url": "https://authors.library.caltech.edu/records/pkt04-3tp50/files/1404.1438v1.pdf" }, "related_objects": [ { "basename": "srep08995.pdf", "url": "https://authors.library.caltech.edu/records/pkt04-3tp50/files/srep08995.pdf" } ], "resource_type": "article", "pub_year": "2015", "author_list": "Zhang, Hang and Minnich, Austin J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/62m14-rtw59", "eprint_id": 50205, "eprint_status": "archive", "datestamp": "2023-08-20 04:58:48", "lastmod": "2023-10-17 22:50:54", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "A. J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Phonon heat conduction in layered anisotropic crystals", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 American Physical Society.\n\nReceived 17 September 2014; revised manuscript received 9 December 2014; published 17 February 2015.\n\nThe author thanks Chengyun Hua and Ding Ding for performing several integrals. This work was sponsored in part by Robert Bosch LLC through Bosch Energy Research Network Grant No. 13.01.CC11, by the National Science Foundation under Grant No. CBET CAREER 1254213, and by Boeing under the Boeing-Caltech Strategic Research & Development Relationship Agreement.\n\nPublished - PhysRevB.91.085206.pdf
Submitted - 1409.5364v1.pdf
", "abstract": "The thermal properties of anisotropic crystals are of both fundamental and practical interest, but transport phenomena in anisotropic materials such as graphite remain poorly understood because solutions of the Boltzmann equation often assume isotropy. Here, we extend an analytic solution of the transient, frequency-dependent Boltzmann equation to highly anisotropic solids and examine its predictions for graphite. We show that this simple model predicts key results, such as long c -axis phonon mean free paths and a negative correlation of cross-plane thermal conductivity with in-plane group velocity, that were previously observed with computationally expensive molecular-dynamics simulations. Further, using our analytic solution, we demonstrate a method to reconstruct the anisotropic mean free path spectrum of crystals with arbitrary dispersion relations without any prior knowledge of their harmonic or anharmonic properties using observations of quasiballistic heat conduction. These results provide a useful analytic framework to understand thermal transport in anisotropic crystals.", "date": "2015-02-15", "date_type": "published", "publication": "Physical Review B", "volume": "91", "number": "8", "publisher": "American Physical Society", "pagerange": "Art. No. 085206", "id_number": "CaltechAUTHORS:20141006-102957226", "issn": "1098-0121", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141006-102957226", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Robert Bosch LLC Bosch Energy Research Network", "grant_number": "13.01.CC11" }, { "agency": "NSF", "grant_number": "CBET 1254213" }, { "agency": "Boeing-Caltech Strategic Research & Development Relationship Agreement" } ] }, "doi": "10.1103/PhysRevB.91.085206", "primary_object": { "basename": "1409.5364v1.pdf", "url": "https://authors.library.caltech.edu/records/62m14-rtw59/files/1409.5364v1.pdf" }, "related_objects": [ { "basename": "PhysRevB.91.085206.pdf", "url": "https://authors.library.caltech.edu/records/62m14-rtw59/files/PhysRevB.91.085206.pdf" } ], "resource_type": "article", "pub_year": "2015", "author_list": "Minnich, A. J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/9tdk2-zg613", "eprint_id": 55262, "eprint_status": "archive", "datestamp": "2023-08-22 14:57:17", "lastmod": "2023-10-20 22:02:18", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "A. J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Advances in the measurement and computation of thermal phonon transport properties", "ispublished": "pub", "full_text_status": "restricted", "keywords": "thermal transport; heat conduction; phonons; ballistic transport; thermoelectrics", "note": "\u00a9 2015 IOP Publishing Ltd.\n\nReceived 2 May 2014; Revised 28 November 2014; Accepted for publication 4 December 2014; Published 21 January 2015.\n\nThe author thanks S Lee, L Zheng, Z Tian, J Garg and O Delaire for commenting on the manuscript. This work was sponsored in part by R Bosch LLC through Bosch Energy Research Network Grant no. 13.01.CC11, by the National Science Foundation under grant no. CAREER CBET 1254213, and\nby Boeing under the Boeing-Caltech Strategic Research &\nDevelopment Relationship Agreement.", "abstract": "Heat conduction by phonons is a ubiquitous process that incorporates a wide range of physics and plays an essential role in applications ranging from space power generation to LED lighting. Heat conduction has been studied for over two hundred years, yet many of the microscopic details have remained unknown in most crystalline solids, including which phonon\u2013phonon interactions are primarily responsible for thermal resistance and how heat is distributed among the broad thermal spectrum. This lack of knowledge was the result of limitations on the available tools to study heat conduction. However, recent advances in both computation and experiment are enabling an unprecedented microscopic view of thermal transport by phonons in both bulk and nanostructured crystals, from the level of atomic bonding to mesoscopic transport in complex devices. In this topical review, we examine these techniques and the microscopic insights gained into the science and engineering of heat conduction.", "date": "2015-02-11", "date_type": "published", "publication": "Journal of Physics: Condensed Matter", "volume": "27", "number": "5", "publisher": "IOP", "pagerange": "Art. No. 053202", "id_number": "CaltechAUTHORS:20150226-122003613", "issn": "0953-8984", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150226-122003613", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Bosch Energy Research Network", "grant_number": "13.01.CC11" }, { "agency": "NSF", "grant_number": "CBET-1254213" }, { "agency": "Boeing-Caltech Strategic Research & Development Relationship Agreement" } ] }, "doi": "10.1088/0953-8984/27/5/053202", "resource_type": "article", "pub_year": "2015", "author_list": "Minnich, A. J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/dnc7e-zkt83", "eprint_id": 50041, "eprint_status": "archive", "datestamp": "2023-08-20 04:42:59", "lastmod": "2023-10-17 22:27:47", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Schleeh-Joel", "name": { "family": "Schleeh", "given": "J." } }, { "id": "Mateos-J", "name": { "family": "Mateos", "given": "J." } }, { "id": "\u00cd\u00f1iguez-de-la-Torre-I", "name": { "family": "\u00cd\u00f1iguez-de-la-Torre", "given": "I." } }, { "id": "Wadefalk-Niklas", "name": { "family": "Wadefalk", "given": "N." } }, { "id": "Nilsson-Per-\u00c5ke", "name": { "family": "Nilsson", "given": "P.-A." } }, { "id": "Grahn-Jan", "name": { "family": "Grahn", "given": "J." } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "A. J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Phonon black-body radiation limit for heat dissipation in electronics", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2014 Macmillan Publishers Limited. \n\nReceived 11 June 2014; accepted 3 October 2014; published online 10 November 2014. \n\nThe authors thank S. Weinreb for useful discussions. I.I-d-l-T. and J.M. were partially supported by the Spanish MINECO through project TEC2013-41640-R and by the Consejeria de Educaci\u00f3n de la Junta de Castilla y Le\u00f3n through project SA052U13. J.S., N.W., P.A.N. and J.G. were supported by the GigaHertz Centre in a joint research project financed by the Swedish Governmental Agency of Innovation Systems (VINNOVA), Chalmers University of Technology, Omnisys Instruments AB, Wasa Millimeter Wave, Low Noise Factory and SP Technical Research Institute of Sweden. A.J.M. was supported by a Caltech startup fund and by the National Science Foundation under Grant no. CAREER CBET 1254213.\n\nSupplemental Material - nmat4126-s1.pdf
", "abstract": "Thermal dissipation at the active region of electronic devices is a fundamental process of considerable importance. Inadequate heat dissipation can lead to prohibitively large temperature rises that degrade performance and intensive efforts are under way to mitigate this self-heating. At room temperature, thermal resistance is due to scattering, often by defects and interfaces in the active region, that impedes the transport of phonons. Here, we demonstrate that heat dissipation in widely used cryogenic electronic devices instead occurs by phonon black-body radiation with the complete absence of scattering, leading to large self-heating at cryogenic temperatures and setting a key limit on the noise floor. Our result has important implications for the many fields that require ultralow-noise electronic devices.", "date": "2015-02", "date_type": "published", "publication": "Nature Materials", "volume": "14", "number": "2", "publisher": "Nature Publishing Group", "pagerange": "187-192", "id_number": "CaltechAUTHORS:20140925-151645385", "issn": "1476-1122", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140925-151645385", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Ministerio de Econom\u00eda, Industria y Competitividad (MINECO)", "grant_number": "TEC2013-41640-R" }, { "agency": "Consejeria de Educaci\u00f3n de la Junta de Castilla y Le\u00f3n", "grant_number": "SA052U13" }, { "agency": "GigaHertz Centre" }, { "agency": "Swedish Governmental Agency of Innovation Systems (VINNOVA)" }, { "agency": "Chalmers University of Technology" }, { "agency": "Omnisys Instruments AB" }, { "agency": "Wasa Millimeter Wave" }, { "agency": "Low Noise Factory" }, { "agency": "SP Technical Research Institute of Sweden" }, { "agency": "Caltech" }, { "agency": "NSF", "grant_number": "CBET-1254213" } ] }, "doi": "10.1038/nmat4126", "primary_object": { "basename": "nmat4126-s1.pdf", "url": "https://authors.library.caltech.edu/records/dnc7e-zkt83/files/nmat4126-s1.pdf" }, "resource_type": "article", "pub_year": "2015", "author_list": "Schleeh, J.; Mateos, J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/2vykq-yjx44", "eprint_id": 55948, "eprint_status": "archive", "datestamp": "2023-08-20 03:57:09", "lastmod": "2023-10-20 23:28:08", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hua-Chengyun", "name": { "family": "Hua", "given": "Chengyun" }, "orcid": "0000-0003-3587-8342" }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Analytical Green's function of the multidimensional frequency-dependent phonon Boltzmann equation", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2014 American Physical Society.\n\nReceived 19 August 2014; revised manuscript received 20 November 2014; published 31 December 2014.\n\nThis work was sponsored in part by Robert Bosch, LLC, through Bosch Energy Research Network Grant No. 13.01.CC11, by the National Science Foundation under Grant No. CBET CAREER 1254213, and by Boeing under the Boeing-Caltech Strategic Research and Development Relationship Agreement.\n\nPublished - PhysRevB.90.214306.pdf
", "abstract": "Thermal phonon transport at length scales comparable to mean free paths is governed by the Boltzmann equation, which is challenging to solve due to its high dimensionality. Here, we present an analytical Green's function for the frequency-dependent, multidimensional Boltzmann equation under the relaxation-time approximation. The new analytical solution is valid from diffusive to ballistic transport regimes and rigorously includes frequency dependence of phonon properties. We demonstrate that our result enables simple closed-form solutions for a number of multidimensional problems for which the only prior solution methods have been computationally expensive numerical simulations.", "date": "2014-12-01", "date_type": "published", "publication": "Physical Review B", "volume": "90", "number": "21", "publisher": "American Physical Society", "pagerange": "Art. No. 214306", "id_number": "CaltechAUTHORS:20150320-133005322", "issn": "1098-0121", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150320-133005322", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Bosch Energy Research Network", "grant_number": "13.01.CC11" }, { "agency": "NSF CAREER", "grant_number": "CBET 1254213" }, { "agency": "Boeing-Caltech Strategic Research and Development Relationship Agreement" } ] }, "doi": "10.1103/PhysRevB.90.214306", "primary_object": { "basename": "PhysRevB.90.214306.pdf", "url": "https://authors.library.caltech.edu/records/2vykq-yjx44/files/PhysRevB.90.214306.pdf" }, "resource_type": "article", "pub_year": "2014", "author_list": "Hua, Chengyun and Minnich, Austin J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ercph-k0a35", "eprint_id": 45678, "eprint_status": "archive", "datestamp": "2023-08-20 03:45:37", "lastmod": "2023-10-26 18:09:34", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hua-C", "name": { "family": "Hua", "given": "Chengyun" } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Importance of frequency-dependent grain boundary scattering in nanocrystalline silicon and silicon-germanium thermoelectrics", "ispublished": "pub", "full_text_status": "public", "keywords": "grain boundary scattering, Monte Carlo simulations, nanocrystalline thermoelectrics", "note": "\u00a9 2014 IOP Publishing Ltd. Received 30 April 2014, revised 30 June 2014. Accepted for publication 24 July 2014. Published 14 November 2014.\n\nThe authors thank J.P. Peraud and N.G. Hadjicontantinou for useful discussions. This work was sponsored in part by Robert Bosch LLC through Bosch Energy Research Network\nGrant no. 13.01.CC11, by the National Science Foundation under Grant no. CBET CAREER 1254213, and by Boeing under the Boeing-Caltech Strategic Research & Development Relationship\nAgreement.\n\nSubmitted - 1404.7847v1.pdf
", "abstract": "Nanocrystalline silicon and silicon-germanium alloys are promising thermoelectric materials that have achieved substantially improved figure of merits compared to their bulk counterparts. This enhancement is typically attributed to a reduction in lattice thermal conductivity by phonon scattering at grain boundaries. However, further improvements are difficult to achieve because grain boundary scattering is poorly understood, with recent experimental observations suggesting that the phonon transmissivity may depend on phonon frequency rather than being constant as in the commonly used gray model. Here, we examine the impact of frequency-dependent grain boundary scattering in nanocrystalline silicon and silicon-germanium alloys in a realistic 3D geometry using frequency-dependent variance-reduced Monte Carlo simulations. We find that the grain boundary may not be as effective as predicted by the gray model in scattering certain phonons, with a substantial amount of heat being carried by low frequency phonons with mean free paths longer than the grain size. Our result will help guide the design of more efficient thermoelectrics.", "date": "2014-12", "date_type": "published", "publication": "Semiconductor Science and Technology", "volume": "29", "number": "12", "publisher": "IOP", "pagerange": "Art. No. 124004", "id_number": "CaltechAUTHORS:20140512-105243137", "issn": "0268-1242", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140512-105243137", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Bosch Energy Research Network", "grant_number": "13.01.CC11" }, { "agency": "NSF", "grant_number": "CBET CAREER 1254213" }, { "agency": "Boeing-Caltech Strategic Research & Development Relationship Agreement" } ] }, "doi": "10.1088/0268-1242/29/12/124004", "primary_object": { "basename": "1404.7847v1.pdf", "url": "https://authors.library.caltech.edu/records/ercph-k0a35/files/1404.7847v1.pdf" }, "resource_type": "article", "pub_year": "2014", "author_list": "Hua, Chengyun and Minnich, Austin J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/wz221-wbb21", "eprint_id": 50835, "eprint_status": "archive", "datestamp": "2023-08-20 03:18:39", "lastmod": "2023-10-18 14:34:20", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hua-C", "name": { "family": "Hua", "given": "Chengyun" } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Cross-plane heat conduction in thin solid films", "ispublished": "unpub", "full_text_status": "public", "note": "This work was sponsored in part by Robert Bosch LLC through Bosch Energy Research\nNetwork Grant no. 13.01.CC11, by the National Science Foundation under Grant no. CBET CAREER 1254213, and by Boeing under the Boeing-Caltech Strategic Research & Development Relationship Agreement.\n\nSubmitted - 1410.2845.pdf
", "abstract": "Cross-plane heat transport in thin films with thickness comparable to the phonon mean free paths is of both fundamental and practical interest. However, physical insight is difficult to obtain for the cross-plane geometry due to the challenge of solving the Boltzmann equation in a finite domain. Here, we present a semi-analytical series expansion method to solve the transient, frequency-dependent Boltzmann transport equation that is valid from the diffusive to ballistic transport regimes and rigorously includes frequency-dependence of phonon properties. Further, our method is more than three orders of magnitude faster than prior numerical methods and provides a simple analytical expression for the thermal conductivity as a function of film thickness. Our result enables a more accurate understanding of heat conduction in thin films.", "date": "2014-10-27", "date_type": "published", "id_number": "CaltechAUTHORS:20141027-095518248", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141027-095518248", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Robert Bosch LLC Bosch Energy Research Network", "grant_number": "13.01.CC11" }, { "agency": "NSF CBET CAREER", "grant_number": "1254213" }, { "agency": "Boeing-Caltech Strategic Research & Development Relationship Agreement" } ] }, "doi": "10.48550/arXiv.1410.2845", "primary_object": { "basename": "1410.2845.pdf", "url": "https://authors.library.caltech.edu/records/wz221-wbb21/files/1410.2845.pdf" }, "resource_type": "monograph", "pub_year": "2014", "author_list": "Hua, Chengyun and Minnich, Austin J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/6bbd8-cjp98", "eprint_id": 50217, "eprint_status": "archive", "datestamp": "2023-08-20 02:18:30", "lastmod": "2023-10-17 22:51:22", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Maasilta-I", "name": { "family": "Maasilta", "given": "Ilari" } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Heat under the microscope", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2014 AIP Publishing LLC.\n\nPublished - PT.3.2479.pdf
", "abstract": "Recent advances in computational and spectroscopic tools offer new insights into the nature of thermal conduction at ever-finer length scales and ways to control it.", "date": "2014-08", "date_type": "published", "publication": "Physics Today", "volume": "67", "number": "8", "publisher": "American Institute of Physics", "pagerange": "27-32", "id_number": "CaltechAUTHORS:20141006-141042223", "issn": "0031-9228", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141006-141042223", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1063/PT.3.2479", "primary_object": { "basename": "PT.3.2479.pdf", "url": "https://authors.library.caltech.edu/records/6bbd8-cjp98/files/PT.3.2479.pdf" }, "resource_type": "article", "pub_year": "2014", "author_list": "Maasilta, Ilari and Minnich, Austin J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/n5en1-jpp06", "eprint_id": 45815, "eprint_status": "archive", "datestamp": "2023-08-20 00:53:18", "lastmod": "2023-10-26 18:28:29", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "A. J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Towards a microscopic understanding of phonon heat conduction", "ispublished": "unpub", "full_text_status": "public", "note": "The author thanks Sangyeop Lee, Lingping Zheng, Zhiting Tian, Jivtesh Garg, and\nOlivier Delaire for commenting on the manuscript. This work was sponsored in part by\nRobert Bosch LLC through Bosch Energy Research Network Grant no. 13.01.CC11, by the\nNational Science Foundation under Grant no. CBET 1254213, and by Boeing under the\nBoeing-Caltech Strategic Research & Development Relationship Agreement.\n\nSubmitted - 1405.0532.pdf
", "abstract": "Heat conduction by phonons is a ubiquitous process that incorporates a wide range of\nphysics and plays an essential role in applications ranging from space power generation to\nLED lighting. Heat conduction has been studied for over two hundred years, yet many\nmicroscopic aspects of heat conduction have remained unclear in most crystalline solids,\nincluding which phonons carry heat and how natural and artificial structures scatter specific\nphonons. Fortunately, recent advances in both computation and experiment are enabling\nan unprecedented microscopic view of thermal transport by phonons. In this topical review,\nwe provide an overview of these methods, the insights they are providing, and their impact\non the science and engineering of heat conduction.", "date": "2014-05-20", "date_type": "published", "id_number": "CaltechAUTHORS:20140519-090523782", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140519-090523782", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Bosch Energy Research Network", "grant_number": "13.01.CC11" }, { "agency": "NSF", "grant_number": "CBET 1254213" }, { "agency": "Boeing-Caltech Strategic Research & Development Relationship Agreement" } ] }, "doi": "10.48550/arXiv.1405.0532", "primary_object": { "basename": "1405.0532.pdf", "url": "https://authors.library.caltech.edu/records/n5en1-jpp06/files/1405.0532.pdf" }, "resource_type": "monograph", "pub_year": "2014", "author_list": "Minnich, A. J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/6m85q-jgw24", "eprint_id": 45059, "eprint_status": "archive", "datestamp": "2023-08-20 00:56:57", "lastmod": "2023-10-26 17:31:57", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Ravichandran-Navaneetha-K", "name": { "family": "Ravichandran", "given": "Navaneetha K." } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Coherent and Incoherent Thermal Transport in Nanomeshes", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2014 American Physical Society.\nReceived 12 November 2013; revised manuscript received 17 March 2014; published 27 May 2014.\nThis work is part of the \"Light-Material Interactions in\nEnergy Conversion\" Energy Frontier Research Center funded\nby the US Department of Energy, Office of Science, Office of\nBasic Energy Sciences under Award No. DE-SC0001293.\n\nPublished - PhysRevB.89.205432.pdf
Submitted - 1403.7647v1.pdf
", "abstract": "Coherent thermal transport in nanopatterned structures is a topic of considerable interest, but whether it occurs in certain structures remains unclear due to a poor understanding of which phonons conduct heat. Here, we perform fully three-dimensional, frequency-dependent simulations of thermal transport in nanomeshes by solving the Boltzmann transport equation with an efficient Monte Carlo method. From the spectral information in our simulations, we show that thermal transport in nanostructures that can be created with available lithographic techniques is dominated by incoherent boundary scattering at room temperature. Our result provides important insights into the conditions required for coherent thermal transport to occur in artificial structures.", "date": "2014-05-15", "date_type": "published", "publication": "Physical Review B", "volume": "89", "number": "20", "publisher": "American Physical Society", "pagerange": "Art. No. 205432", "id_number": "CaltechAUTHORS:20140421-080824072", "issn": "1098-0121", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140421-080824072", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE) Light Material Interactions Energy Frontier Research Center", "grant_number": "DE-SC0001293" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" } ] }, "doi": "10.1103/PhysRevB.89.205432", "primary_object": { "basename": "1403.7647v1.pdf", "url": "https://authors.library.caltech.edu/records/6m85q-jgw24/files/1403.7647v1.pdf" }, "related_objects": [ { "basename": "PhysRevB.89.205432.pdf", "url": "https://authors.library.caltech.edu/records/6m85q-jgw24/files/PhysRevB.89.205432.pdf" } ], "resource_type": "article", "pub_year": "2014", "author_list": "Ravichandran, Navaneetha K. and Minnich, Austin J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/wj6yc-4kk56", "eprint_id": 43866, "eprint_status": "archive", "datestamp": "2023-08-20 00:20:59", "lastmod": "2023-10-25 23:57:26", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Ding-D", "name": { "family": "Ding", "given": "D." } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "A. J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Radial Quasiballistic Transport in Time-Domain Thermoreflectance Studied Using Monte Carlo Simulations", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2014 AIP Publishing LLC.\n\nReceived 30 January 2014; accepted 26 March 2014; published online 8 April 2014.\n\nThe authors thank R. B. Wilson and David G. Cahill for\nuseful discussions. This work was sponsored in part by\nRobert Bosch LLC through Bosch Energy Research Network\nGrant No. 13.01.CC11, by the National Science Foundation\nunder CAREER Grant No. CBET 1254213, and by Boeing\nunder the Boeing-Caltech Strategic Research and\nDevelopment Relationship Agreement. D. Ding gratefully\nacknowledges the support by the Agency for Science,\nTechnology and Research (Singapore).\n\nPublished - 1.4870811.pdf
Submitted - 1402.1114v1.pdf
", "abstract": "Recently, a pump beam size dependence of thermal conductivity was observed in Si at cryogenic temperatures using time-domain thermal reflectance (TDTR). These observations were attributed to quasiballistic phonon transport, but the interpretation of the measurements has been semi-empirical. Here, we present a numerical study of the heat conduction that occurs in the full 3D geometry of a TDTR experiment, including an interface, using the Boltzmann transport equation. We identify the radial suppression function that describes the suppression in heat flux, compared to Fourier's law, that occurs due to quasiballistic transport and demonstrate good agreement with experimental data. We also discuss unresolved discrepancies that are important topics for future study.", "date": "2014-04-07", "date_type": "published", "publication": "Applied Physics Letters", "volume": "104", "number": "14", "publisher": "American Institute of Physics", "pagerange": "Art. No. 143104", "id_number": "CaltechAUTHORS:20140219-084813829", "issn": "0003-6951", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140219-084813829", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Robert Bosch LLC Bosch Energy Research Network", "grant_number": "13.01.CC11" }, { "agency": "NSF", "grant_number": "CBET 1254213" }, { "agency": "Boeing-Caltech Strategic Research & Development Relationship Agreement" }, { "agency": "Agency for Science, Technology and Research (Singapore)" } ] }, "doi": "10.1063/1.4870811", "primary_object": { "basename": "1.4870811.pdf", "url": "https://authors.library.caltech.edu/records/wj6yc-4kk56/files/1.4870811.pdf" }, "related_objects": [ { "basename": "1402.1114v1.pdf", "url": "https://authors.library.caltech.edu/records/wj6yc-4kk56/files/1402.1114v1.pdf" } ], "resource_type": "article", "pub_year": "2014", "author_list": "Ding, D. and Minnich, A. J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/mbdvx-03n88", "eprint_id": 44885, "eprint_status": "archive", "datestamp": "2023-08-19 23:48:30", "lastmod": "2023-10-26 17:01:23", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hua-C", "name": { "family": "Hua", "given": "Chengyun" } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Transport regimes in quasiballistic heat conduction", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2014 American Physical Society.\n\nPublished 14 March 2014; Received 9 September 2013.\n\nThe authors thank Kimberlee Collins and Gang Chen for useful discussions and for providing the PbSe data. This work was sponsored in part by Robert Bosch LLC through Bosch Energy Research Network Grant No. 13.01.CC11, by the National Science Foundation under Career Grant No. CBET 1254213, and by Boeing under the Boeing-Caltech Strategic Research & Development Relationship Agreement.\n\nPublished - PhysRevB.89.094302.pdf
", "abstract": "Transient grating (TG) spectroscopy is an important experimental technique to measure mean-free-path (MFP) spectra using observations of quasiballistic heat conduction. To obtain MFP spectra, the measurements must be interpreted within the framework of the frequency-dependent Boltzmann transport equation (BTE), but previous solutions have restricted validity due to simplifying assumptions. Here we analyze heat conduction in TG using a new analytical solution of the frequency-dependent BTE that accurately describes thermal transport from the diffusive to ballistic regimes. We demonstrate that our result enables a more accurate measurement of MFP spectra and thus will lead to an improved understanding of heat conduction in solids.", "date": "2014-03-01", "date_type": "published", "publication": "Physical Review A", "volume": "89", "number": "9", "publisher": "American Physical Society", "pagerange": "Art. No. 094302", "id_number": "CaltechAUTHORS:20140411-093446830", "issn": "1050-2947", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140411-093446830", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Bosch Energy Research Network", "grant_number": "13.01.CC11" }, { "agency": "NSF", "grant_number": "CBET 1254213" }, { "agency": "Boeing-Caltech Strategic Research & Development Relationship Agreement" } ] }, "doi": "10.1103/PhysRevB.89.094302", "primary_object": { "basename": "PhysRevB.89.094302.pdf", "url": "https://authors.library.caltech.edu/records/mbdvx-03n88/files/PhysRevB.89.094302.pdf" }, "resource_type": "article", "pub_year": "2014", "author_list": "Hua, Chengyun and Minnich, Austin J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ahv7v-7ts26", "eprint_id": 43858, "eprint_status": "archive", "datestamp": "2023-08-19 23:29:15", "lastmod": "2023-10-25 23:57:01", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hua-C", "name": { "family": "Hua", "given": "Chengyun" } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Quasiballistc Heat Conduction in Transient Grating Spectroscopy", "ispublished": "unpub", "full_text_status": "public", "note": "The authors would like to thank Kimberlee Collins and Gang Chen for useful discussions\nand for providing the PbSe data. This work was sponsored in part by Robert Bosch LLC\nthrough Bosch Energy Research Network Grant no. 13.01.CC11, by the National Science\nFoundation under Grant no. CBET 1254213, and by Boeing under the Boeing-Caltech\nStrategic Research & Development Relationship Agreement.\n\nSubmitted - 1402.1449v1.pdf
", "abstract": "Transient grating (TG) spectroscopy is an important experimental technique to measure mean free path (MFP) spectra using observations of quasiballistic heat conduction. To obtain MFP spectra, the measurements must be interpreted within the framework of the frequency-dependent Boltzmann transport equation (BTE), but previous solutions have restricted validity due to simplifying assumptions. Here, we analyze heat conduction in TG using a new analytical solution of the frequency-dependent BTE that accurately describes thermal transport from the diffusive to ballistic regimes. We demonstrate that our result enables a more accurate measurement of MFP spectra and thus will lead to an improved understanding of heat conduction in solids.", "date": "2014-02-18", "date_type": "published", "id_number": "CaltechAUTHORS:20140218-150702699", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140218-150702699", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Robert Bosch LLC Bosch Energy Research Network", "grant_number": "13.01.CC11" }, { "agency": "NSF", "grant_number": "CBET 1254213" }, { "agency": "Boeing-Caltech Strategic Research & Development Relationship Agreement" } ] }, "doi": "10.48550/arXiv.1402.1449", "primary_object": { "basename": "1402.1449v1.pdf", "url": "https://authors.library.caltech.edu/records/ahv7v-7ts26/files/1402.1449v1.pdf" }, "resource_type": "monograph", "pub_year": "2014", "author_list": "Hua, Chengyun and Minnich, Austin J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ekp5q-mh523", "eprint_id": 45262, "eprint_status": "archive", "datestamp": "2023-08-19 23:24:31", "lastmod": "2023-10-20 22:53:36", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lo-F-S", "name": { "family": "Lo", "given": "F. S." } }, { "id": "Lu-P-S", "name": { "family": "Lu", "given": "P. S." } }, { "id": "Ragan-Kelley-B", "name": { "family": "Ragan-Kelley", "given": "B." } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "A." }, "orcid": "0000-0002-9671-9540" }, { "id": "Lee-T-H", "name": { "family": "Lee", "given": "T. H." } }, { "id": "Lin-M-C", "name": { "family": "Lin", "given": "M. C." } }, { "id": "Verboncoeur-J-P", "name": { "family": "Verboncoeur", "given": "J. P." } } ] }, "title": "Modeling a thermionic energy converter using finite-difference time-domain particle-in-cell simulations", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2014 AIP Publishing LLC.\n\nReceived 23 October 2013; accepted 3 February 2014; published online 25 February 2014.\n\nWork supported by the National Science Council, Taiwan,\nR.O.C. under Grant No. NSC 96-2112-M-030-004-MY3, NCTS, and NCHC, which provides the computing resources.\n\nPublished - 1.4865828.pdf
Erratum - 1.4905178.pdf
", "abstract": "A thermionic energy converter (TEC) is a static device that converts heat directly into electricity by boiling electrons off a hot emitter surface across a small inter-electrode gap to a cooler collector surface. The main challenge in TECs is overcoming the space charge limit, which limits the current transmitted across a gap of a given voltage and width. We have verified the feasibility of studying and developing a TEC using a bounded finite-difference time-domain particle-in-cell plasma simulation code, OOPD1, developed by Plasma Theory and Simulation Group, formerly at UC Berkeley and now at Michigan State University. In this preliminary work, a TEC has been modeled kinetically using OOPD1, and the accuracy has been verified by comparing with an analytically solvable case, giving good agreement. With further improvement of the code, one will be able to quickly and cheaply analyze space charge effects, and seek designs that mitigate the space charge effect, allowing TECs to become more efficient and cost-effective.", "date": "2014-02", "date_type": "published", "publication": "Physics of Plasmas", "volume": "21", "number": "2", "publisher": "American Institute of Physics", "pagerange": "Art. No. 023510", "id_number": "CaltechAUTHORS:20140429-083059796", "issn": "1070-664X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140429-083059796", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "National Science Council, Taiwan", "grant_number": "NSC 96-2112-M-030-004-MY3" }, { "agency": "NCTS" }, { "agency": "NCHC" } ] }, "doi": "10.1063/1.4865828", "primary_object": { "basename": "1.4865828.pdf", "url": "https://authors.library.caltech.edu/records/ekp5q-mh523/files/1.4865828.pdf" }, "related_objects": [ { "basename": "1.4905178.pdf", "url": "https://authors.library.caltech.edu/records/ekp5q-mh523/files/1.4905178.pdf" } ], "resource_type": "article", "pub_year": "2014", "author_list": "Lo, F. S.; Lu, P. S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/jd7dz-dqx75", "eprint_id": 39315, "eprint_status": "archive", "datestamp": "2023-08-19 20:07:14", "lastmod": "2023-10-24 16:40:32", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Naturally glassy crystals", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2013 Macmillan Publishers Limited.\nPublished online 05 June 2013.", "abstract": "Spontaneously formed natural nanostructures are responsible for a glass-like thermal conductivity in a perfectly crystalline semiconductor.", "date": "2013-06", "date_type": "published", "publication": "Nature Nanotechnology", "volume": "8", "number": "6", "publisher": "Nature Publishing Group", "pagerange": "392-393", "id_number": "CaltechAUTHORS:20130711-104354370", "issn": "1748-3387", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130711-104354370", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1038/nnano.2013.106", "resource_type": "article", "pub_year": "2013", "author_list": "Minnich, Austin J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/qswjm-2v852", "eprint_id": 106336, "eprint_status": "archive", "datestamp": "2023-08-19 14:21:27", "lastmod": "2023-10-20 23:21:58", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Johnson-Jeremy-A", "name": { "family": "Johnson", "given": "Jeremy A." }, "orcid": "0000-0001-9808-7172" }, { "id": "Maznev-A-A", "name": { "family": "Maznev", "given": "A. A." } }, { "id": "Cuffe-J", "name": { "family": "Cuffe", "given": "John" }, "orcid": "0000-0003-2915-5383" }, { "id": "Eliason-J-K", "name": { "family": "Eliason", "given": "Jeffrey K." } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" }, { "id": "Kehoe-Timothy", "name": { "family": "Kehoe", "given": "Timothy" } }, { "id": "Sotomayor-Torres-C-M", "name": { "family": "Sotomayor Torres", "given": "Clivia M." }, "orcid": "0000-0001-9986-2716" }, { "id": "Chen-Gang", "name": { "family": "Chen", "given": "Gang" } }, { "id": "Nelson-K-A", "name": { "family": "Nelson", "given": "Keith A." } } ] }, "title": "Direct Measurement of Room-Temperature Nondiffusive Thermal Transport Over Micron Distances in a Silicon Membrane", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2013 American Physical Society. \n\nReceived 29 April 2012; published 8 January 2013. \n\nThis work was supported as part of the S3TEC Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Basic Energy Sciences under Award No. DE-SC0001299/DE-FG02-09ER46577 (experimental setup and data analysis). This work was also partially supported by projects NANOPOWER, Contract No. 256959; TAILPHOX, Contract No. 233883; NANOFUNCTION, Contract No. 257375; ACPHIN, Contract No. FIS2009-150; and AGAUR, 2009-SGR-150. The samples were fabricated using facilities of the ICTS \"Integrated Nano and Microfabrication Clean Room\" (CSIC-CNM).\n\nPublished - PhysRevLett.110.025901.pdf
Accepted Version - 1204.4735.pdf
Supplemental Material - supplemental.pdf
", "abstract": "The \"textbook\" phonon mean free path of heat carrying phonons in silicon at room temperature is \u223c40\u2009\u2009nm. However, a large contribution to the thermal conductivity comes from low-frequency phonons with much longer mean free paths. We present a simple experiment demonstrating that room-temperature thermal transport in Si significantly deviates from the diffusion model already at micron distances. Absorption of crossed laser pulses in a freestanding silicon membrane sets up a sinusoidal temperature profile that is monitored via diffraction of a probe laser beam. By changing the period of the thermal grating we vary the heat transport distance within the range \u223c1\u201310\u2009\u2009\u03bcm. At small distances, we observe a reduction in the effective thermal conductivity indicating a transition from the diffusive to the ballistic transport regime for the low-frequency part of the phonon spectrum.", "date": "2013-01-11", "date_type": "published", "publication": "Physical Review Letters", "volume": "110", "number": "2", "publisher": "American Physical Society", "pagerange": "Art. No. 025901", "id_number": "CaltechAUTHORS:20201028-142514455", "issn": "0031-9007", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20201028-142514455", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001299" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-09ER46577" }, { "agency": "European Research Council (ERC)", "grant_number": "256959" }, { "agency": "European Research Council (ERC)", "grant_number": "233883" }, { "agency": "European Research Council (ERC)", "grant_number": "257375" }, { "agency": "Ministerio de Econom\u00eda, Industria y Competitividad (MINECO)", "grant_number": "FIS2009-150" }, { "agency": "Generalitat de Catalunya", "grant_number": "2009-SGR-150" } ] }, "doi": "10.1103/physrevlett.110.025901", "primary_object": { "basename": "1204.4735.pdf", "url": "https://authors.library.caltech.edu/records/qswjm-2v852/files/1204.4735.pdf" }, "related_objects": [ { "basename": "PhysRevLett.110.025901.pdf", "url": "https://authors.library.caltech.edu/records/qswjm-2v852/files/PhysRevLett.110.025901.pdf" }, { "basename": "supplemental.pdf", "url": "https://authors.library.caltech.edu/records/qswjm-2v852/files/supplemental.pdf" } ], "resource_type": "article", "pub_year": "2013", "author_list": "Johnson, Jeremy A.; Maznev, A. A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/a3hdk-9ny80", "eprint_id": 36176, "eprint_status": "archive", "datestamp": "2023-08-19 13:31:01", "lastmod": "2023-10-20 22:20:25", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Luckyanova-M-N", "name": { "family": "Luckyanova", "given": "Maria N." } }, { "id": "Garg-J", "name": { "family": "Garg", "given": "Jivtesh" } }, { "id": "Esfarjani-K", "name": { "family": "Esfarjani", "given": "Keivan" } }, { "id": "Jandl-A", "name": { "family": "Jandl", "given": "Adam" } }, { "id": "Bulsara-M-T", "name": { "family": "Bulsara", "given": "Mayank T." } }, { "id": "Schmidt-A-J", "name": { "family": "Schmidt", "given": "Aaron J." } }, { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "Austin J." }, "orcid": "0000-0002-9671-9540" }, { "id": "Chen-Shuo", "name": { "family": "Chen", "given": "Shuo" } }, { "id": "Dresselhaus-M-S", "name": { "family": "Dresselhaus", "given": "Mildred S." } }, { "id": "Ren-Zhifeng", "name": { "family": "Ren", "given": "Zhifeng" }, "orcid": "0000-0001-8233-3332" }, { "id": "Fitzgerald-E-A", "name": { "family": "Fitzgerald", "given": "Eugene A." } }, { "id": "Chen-Gang", "name": { "family": "Chen", "given": "Gang" } } ] }, "title": "Coherent Phonon Heat Conduction in Superlattices", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2013 American Association for the Advancement of Science. \n\nReceived for publication 4 June 2012; Accepted for publication 9 October 2012.\n\nWe thank A. A. Maznev, K. A. Nelson, K. C. Collins, and J. Johnson for helpful discussions. This material is based on work supported as part of the Solid State Solar-Thermal Energy Conversion Center (S3TEC), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under award DE-SC0001299/DE-FG02-09ER46577. M.N.L. was partially supported by the National Science Foundation Graduate Research Fellowship under grant 1122374.\n\nSupplemental Material - Luckyanova.SM.pdf
", "abstract": "The control of heat conduction through the manipulation of phonons as coherent waves in solids is of fundamental interest and could also be exploited in applications, but coherent heat conduction has not been experimentally confirmed. We report the experimental observation of coherent heat conduction through the use of finite-thickness superlattices with varying numbers of periods. The measured thermal conductivity increased linearly with increasing total superlattice thickness over a temperature range from 30 to 150 kelvin, which is consistent with a coherent phonon heat conduction process. First-principles and Green's function\u2013based simulations further support this coherent transport model. Accessing the coherent heat conduction regime opens a new venue for phonon engineering for an array of applications.", "date": "2012-11-16", "date_type": "published", "publication": "Science", "volume": "338", "number": "6109", "publisher": "American Association for the Advancement of Science", "pagerange": "936-939", "id_number": "CaltechAUTHORS:20130104-134419873", "issn": "0036-8075", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130104-134419873", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF Graduate Research Fellowship", "grant_number": "DGE-1122374" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001299" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-09ER46577" } ] }, "doi": "10.1126/science.1225549", "primary_object": { "basename": "Luckyanova.SM.pdf", "url": "https://authors.library.caltech.edu/records/a3hdk-9ny80/files/Luckyanova.SM.pdf" }, "resource_type": "article", "pub_year": "2012", "author_list": "Luckyanova, Maria N.; Garg, Jivtesh; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/qj3vz-rmd60", "eprint_id": 36113, "eprint_status": "archive", "datestamp": "2023-08-19 13:28:34", "lastmod": "2023-10-20 22:15:21", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "A. J." }, "orcid": "0000-0002-9671-9540" } ] }, "title": "Determining Phonon Mean Free Paths from Observations of Quasiballistic Thermal Transport", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2012 American Physical Society.\n\nReceived 6 August 2012; published 13 November 2012.\n\nThe author would like to thank J. A. Tropp for help with\nthe convex optimization, J. P. Peraud and Q. Hao for help\nwith the MC simulations, and A. A. Maznev for useful\ndiscussions. This work was sponsored in part by Robert\nBosch LLC through Bosch Energy Research Network\nGrant No. 13.01.CC11. This work was also supported in\npart by a start-up fund from the California Institute of\nTechnology.\n\nPublished - PhysRevLett.109.205901.pdf
", "abstract": "The mean free paths (MFPs) of thermal phonons are mostly unknown in many solids. Recent work indicates that MFPs may be measured using experimental observations of quasiballistic thermal transport, but the precise relationship between the measurements and the MFP distribution remains unclear. Here, we present a method that can accurately reconstruct the MFP distribution from quasiballistic thermal measurements without any assumptions regarding the phonon scattering mechanisms. Our result will enable a substantially improved understanding of thermal transport in many solids, particularly thermoelectrics.", "date": "2012-11-13", "date_type": "published", "publication": "Physical Review Letters", "volume": "109", "number": "20", "publisher": "American Physical Society", "pagerange": "Art. No. 205901", "id_number": "CaltechAUTHORS:20130102-112244847", "issn": "0031-9007", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130102-112244847", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Robert Bosch LLC Bosch Energy Research Network", "grant_number": "13.01.CC11" }, { "agency": "Caltech" } ] }, "doi": "10.1103/PhysRevLett.109.205901", "primary_object": { "basename": "PhysRevLett.109.205901.pdf", "url": "https://authors.library.caltech.edu/records/qj3vz-rmd60/files/PhysRevLett.109.205901.pdf" }, "resource_type": "article", "pub_year": "2012", "author_list": "Minnich, A. J." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/h3mpr-1js96", "eprint_id": 28774, "eprint_status": "archive", "datestamp": "2023-08-19 08:57:50", "lastmod": "2023-10-24 18:08:51", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Minnich-A-J", "name": { "family": "Minnich", "given": "A. J." }, "orcid": "0000-0002-9671-9540" }, { "id": "Chen-G", "name": { "family": "Chen", "given": "G." } }, { "id": "Mansoor-S", "name": { "family": "Mansoor", "given": "S." } }, { "id": "Yilbas-B-S", "name": { "family": "Yilbas", "given": "B. S." } } ] }, "title": "Quasiballistic heat transfer studied using the frequency-dependent Boltzmann transport equation", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2011 American Physical Society. Received 29 August 2011; revised manuscript received 21 October 2011; published 15 December 2011. The authors would like to thank David Cahill for useful discussions. This material is partially based upon work supported as part of the \"Solid State Solar-Thermal Energy Conversion Center (S3TEC),\" an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences under Award No. DE-SC0001299/DE-FG02-09ER46577 (G.C.), by the Center for Clean Water and Clean Energy at MIT and KFUPM\n(A.M., S.M., B.S.Y.), and by the NSF (A.M.).\n\nPublished - Minnich2011p16751Phys_Rev_B.pdf
", "abstract": "Quasiballistic heat transfer occurs when there is a temperature gradient over length scales comparable to phonon mean free paths (MFPs). This regime has been of interest recently because observation of quasiballistic transport can lead to useful information about phonon MFPs, knowledge of which is essential for engineering nanoscale thermal effects. Here, we use the Boltzmann transport equation (BTE) to understand how observations of quasiballistic transport can yield information about MFPs. We solve the transient, one-dimensional, frequency-dependent BTE for a double-layer structure of a metal film on a substrate, the same geometry that is used in transient thermoreflectance experiments, using a frequency-dependent interface condition. Our results indicate that phonons with MFPs longer than the thermal penetration depth do not contribute to the measured thermal conductivity, providing a means to probe the MFP distribution. We discuss discrepancies between our simulation and experimental observations which offer opportunities for future investigation.", "date": "2011-12-15", "date_type": "published", "publication": "Physical Review B", "volume": "84", "number": "23", "publisher": "American Physical Society", "pagerange": "Art. No. 235207", "id_number": "CaltechAUTHORS:20120113-095151988", "issn": "1098-0121", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120113-095151988", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE) Office of Science, Office of Basic Energy Sciences", "grant_number": "DE-SC0001299/DE-FG02-09ER46577" }, { "agency": "MIT Center for Clean Water and Clean Energy" }, { "agency": "KFUPM" }, { "agency": "NSF" } ] }, "doi": "10.1103/PhysRevB.84.235207", "primary_object": { "basename": "Minnich2011p16751Phys_Rev_B.pdf", "url": "https://authors.library.caltech.edu/records/h3mpr-1js96/files/Minnich2011p16751Phys_Rev_B.pdf" }, "resource_type": "article", "pub_year": "2011", "author_list": "Minnich, A. J.; Chen, G.; et el." } ]