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Torres F, Basaran AC, Schuller IK. Thermal Management in Neuromorphic Materials, Devices, and Networks. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2205098. [PMID: 36067752 DOI: 10.1002/adma.202205098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 08/30/2022] [Indexed: 06/15/2023]
Abstract
Machine learning has experienced unprecedented growth in recent years, often referred to as an "artificial intelligence revolution." Biological systems inspire the fundamental approach for this new computing paradigm: using neural networks to classify large amounts of data into sorting categories. Current machine-learning schemes implement simulated neurons and synapses on standard computers based on a von Neumann architecture. This approach is inefficient in energy consumption, and thermal management, motivating the search for hardware-based systems that imitate the brain. Here, the present state of thermal management of neuromorphic computing technology and the challenges and opportunities of the energy-efficient implementation of neuromorphic devices are considered. The main features of brain-inspired computing and quantum materials for implementing neuromorphic devices are briefly described, the brain criticality and resistive switching-based neuromorphic devices are discussed, the energy and electrical considerations for spiking-based computation are presented, the fundamental features of the brain's thermal regulation are addressed, the physical mechanisms for thermal management and thermoelectric control of materials and neuromorphic devices are analyzed, and challenges and new avenues for implementing energy-efficient computing are described.
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Affiliation(s)
- Felipe Torres
- Physics Department, Faculty of Science, University of Chile, 653, Santiago, 7800024, Chile
- Center of Nanoscience and Nanotechnology (CEDENNA), Av. Ecuador 3493, Santiago, 9170124, Chile
| | - Ali C Basaran
- Department of Physics and Center for Advanced Nanoscience, University of California San Diego, La Jolla, CA, 92093, USA
| | - Ivan K Schuller
- Department of Physics and Center for Advanced Nanoscience, University of California San Diego, La Jolla, CA, 92093, USA
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Sharma V, Okram GS, Kuo YK. Metal to insulator transition, colossal Seebeck coefficient and large violation of Wiedemann-Franz law in nanoscale granular nickel. NANOTECHNOLOGY 2022; 34:035702. [PMID: 36228508 DOI: 10.1088/1361-6528/ac99e6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 10/12/2022] [Indexed: 06/16/2023]
Abstract
We report on the electrical and thermal transport properties of nickel nanoparticles with crystallite size from 23.1 ± 0.3 to 1.3 ± 0.3 nm. These nanoparticles show a systematic metal to insulator transition with the change in the conduction type fromn- to p-type, colossal Seebeck coefficient of 1.87 ± 0.07 mV K-1, and ultralow thermal conductivity of 0.52 ± 0.05 W m-1K-1at 300 K as the crystallite size drops. The electrical resistivity analysis reveals a dramatic change in the electronic excitation spectrum indicating the opening of an energy gap, and cotunneling and Coulomb blockade of the charge carriers. Seebeck coefficient shows transport energy degradation of charge carriers as transport level moves away from the Fermi level with decrease in crystallite size. The Lorenz number rising to about four orders of magnitude in the metallic regimes with decrease in crystallite size, showing a large violation of the Wiedemann-Franz law in these compacted nickel nanoparticles. Such an observation provides the compelling confirmation for unconventional quasiparticle dynamics where the transport of charge and heat is independent of each other. Therefore, such nanoparticles provide an intriguing platform to tune the charge and heat transport, which may be useful for thermoelectrics and heat dissipation in nanocrystal array-based electronics.
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Affiliation(s)
- Vikash Sharma
- UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452001, Madhya Pradesh, India
- Department of Condensed Matter Physics & Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai-400005, India
| | - Gunadhor Singh Okram
- UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452001, Madhya Pradesh, India
| | - Yung-Kang Kuo
- Department of Physics, National Dong-Hwa University, Hualien 97401, Taiwan
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3
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Phonon drag thermal Hall effect in metallic strontium titanate. Proc Natl Acad Sci U S A 2022; 119:e2201975119. [PMID: 35994652 PMCID: PMC9436374 DOI: 10.1073/pnas.2201975119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
SrTiO3, a quantum paralectric, displays a detectable phonon thermal Hall effect (THE). Here, we show that the amplitude of the THE is extremely sensitive to stoichiometry. It drastically decreases upon substitution of a tiny fraction of Sr atoms with Ca, which stabilizes the ferroelectric order. It drastically increases by an even lower density of oxygen vacancies, which turn the system to a dilute metal. The enhancement in the metallic state exceeds by far the sum of the electronic and the phononic contributions. We explain this observation as an outcome of three features: 1) Heat is mostly transported by phonons; 2) the electronic Hall angle is extremely large; and 3) there is substantial momentum exchange between electrons and phonons. Starting from Herring's picture of phonon drag, we arrive to a quantitative account of the enhanced THE. Thus, phonon drag, hitherto detected as an amplifier of thermoelectric coefficients, can generate a purely thermal transverse response in a dilute metal with a large Hall angle. Our results reveal a hitherto-unknown consequence of momentum-conserving collisions between electrons and phonons.
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Zhou W, Yamamoto K, Miura A, Iguchi R, Miura Y, Uchida KI, Sakuraba Y. Seebeck-driven transverse thermoelectric generation. NATURE MATERIALS 2021; 20:463-467. [PMID: 33462463 DOI: 10.1038/s41563-020-00884-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 11/20/2020] [Indexed: 06/12/2023]
Abstract
When a temperature gradient is applied to a closed circuit comprising two different conductors, a charge current is generated via the Seebeck effect1. Here, we utilize the Seebeck-effect-induced charge current to drive 'transverse' thermoelectric generation, which has great potential for energy harvesting and heat sensing applications owing to the orthogonal geometry of the heat-to-charge-current conversion2-9. We found that, in a closed circuit comprising thermoelectric and magnetic materials, artificial hybridization of the Seebeck effect into the anomalous Hall effect10 enables transverse thermoelectric generation with a similar symmetry to the anomalous Nernst effect11-27. Surprisingly, the Seebeck-effect-driven transverse thermopower can be several orders of magnitude larger than the anomalous-Nernst-effect-driven thermopower, which is clearly demonstrated by our experiments using Co2MnGa/Si hybrid materials. The unconventional approach could be a breakthrough in developing applications of transverse thermoelectric generation.
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Affiliation(s)
- Weinan Zhou
- National Institute for Materials Science, Tsukuba, Japan
| | - Kaoru Yamamoto
- National Institute for Materials Science, Tsukuba, Japan
| | - Asuka Miura
- National Institute for Materials Science, Tsukuba, Japan
| | - Ryo Iguchi
- National Institute for Materials Science, Tsukuba, Japan
| | - Yoshio Miura
- National Institute for Materials Science, Tsukuba, Japan
- Center for Spintronics Research Network, Osaka University, Osaka, Japan
| | - Ken-Ichi Uchida
- National Institute for Materials Science, Tsukuba, Japan.
- Institute for Materials Research, Tohoku University, Sendai, Japan.
- Center for Spintronics Research Network, Tohoku University, Sendai, Japan.
| | - Yuya Sakuraba
- National Institute for Materials Science, Tsukuba, Japan.
- PRESTO, Japan Science and Technology Agency, Saitama, Japan.
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Machida Y, Matsumoto N, Isono T, Behnia K. Phonon hydrodynamics and ultrahigh-room-temperature thermal conductivity in thin graphite. Science 2020; 367:309-312. [PMID: 31949080 DOI: 10.1126/science.aaz8043] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 12/18/2019] [Indexed: 01/20/2023]
Abstract
Allotropes of carbon, such as diamond and graphene, are among the best conductors of heat. We monitored the evolution of thermal conductivity in thin graphite as a function of temperature and thickness and found an intimate link between high conductivity, thickness, and phonon hydrodynamics. The room-temperature in-plane thermal conductivity of 8.5-micrometer-thick graphite was 4300 watts per meter-kelvin-a value well above that for diamond and slightly larger than in isotopically purified graphene. Warming enhances thermal diffusivity across a wide temperature range, supporting partially hydrodynamic phonon flow. The enhancement of thermal conductivity that we observed with decreasing thickness points to a correlation between the out-of-plane momentum of phonons and the fraction of momentum-relaxing collisions. We argue that this is due to the extreme phonon dispersion anisotropy in graphite.
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Affiliation(s)
- Yo Machida
- Department of Physics, Gakushuin University, Tokyo 171-8588, Japan.
| | - Nayuta Matsumoto
- Department of Physics, Gakushuin University, Tokyo 171-8588, Japan
| | - Takayuki Isono
- Department of Physics, Gakushuin University, Tokyo 171-8588, Japan
| | - Kamran Behnia
- Laboratoire Physique et Etude de Matériaux (CNRS-Sorbonne Université-ESPCI), PSL Research University, 75005 Paris, France.
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Ge XH, Tian Y, Wu SY, Wu SF. Hyperscaling violating black hole solutions and magneto-thermoelectric DC conductivities in holography. Int J Clin Exp Med 2017. [DOI: 10.1103/physrevd.96.046015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Li X, Xu L, Ding L, Wang J, Shen M, Lu X, Zhu Z, Behnia K. Anomalous Nernst and Righi-Leduc Effects in Mn_{3}Sn: Berry Curvature and Entropy Flow. PHYSICAL REVIEW LETTERS 2017; 119:056601. [PMID: 28949739 DOI: 10.1103/physrevlett.119.056601] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Indexed: 05/16/2023]
Abstract
We present a study of electric, thermal and thermoelectric response in noncollinear antiferromagnet Mn_{3}Sn, which hosts a large anomalous Hall effect (AHE). Berry curvature generates off-diagonal thermal (Righi-Leduc) and thermoelectric (Nernst) signals, which are detectable at room temperature and invertible with a small magnetic field. The thermal and electrical Hall conductivities respect the Wiedemann-Franz law, implying that the transverse currents induced by the Berry curvature are carried by Fermi surface quasiparticles. In contrast to conventional ferromagnets, the anomalous Lorenz number remains close to the Sommerfeld number over the whole temperature range of study, excluding any contribution by inelastic scattering and pointing to the Berry curvature as the unique source of AHE. The anomalous off-diagonal thermo-electric and Hall conductivities are strongly temperature dependent and their ratio is close to k_{B}/e.
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Affiliation(s)
- Xiaokang Li
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Liangcai Xu
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Linchao Ding
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Jinhua Wang
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Mingsong Shen
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Xiufang Lu
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Zengwei Zhu
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Kamran Behnia
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
- Laboratoire de Physique Et d'Etude des Matériaux (UPMC-CNRS), ESPCI Paris, PSL Research University, 75005 Paris, France
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8
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Abstract
The thermal diffusivity in the [Formula: see text] plane of underdoped YBCO crystals is measured by means of a local optical technique in the temperature range of 25-300 K. The phase delay between a point heat source and a set of detection points around it allows for high-resolution measurement of the thermal diffusivity and its in-plane anisotropy. Although the magnitude of the diffusivity may suggest that it originates from phonons, its anisotropy is comparable with reported values of the electrical resistivity anisotropy. Furthermore, the anisotropy drops sharply below the charge order transition, again similar to the electrical resistivity anisotropy. Both of these observations suggest that the thermal diffusivity has pronounced electronic as well as phononic character. At the same time, the small electrical and thermal conductivities at high temperatures imply that neither well-defined electron nor phonon quasiparticles are present in this material. We interpret our results through a strongly interacting incoherent electron-phonon "soup" picture characterized by a diffusion constant [Formula: see text], where [Formula: see text] is the soup velocity, and scattering of both electrons and phonons saturates a quantum thermal relaxation time [Formula: see text].
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9
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Lee S, Hippalgaonkar K, Yang F, Hong J, Ko C, Suh J, Liu K, Wang K, Urban JJ, Zhang X, Dames C, Hartnoll SA, Delaire O, Wu J. Anomalously low electronic thermal conductivity in metallic vanadium dioxide. Science 2017; 355:371-374. [DOI: 10.1126/science.aag0410] [Citation(s) in RCA: 230] [Impact Index Per Article: 32.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Accepted: 12/22/2016] [Indexed: 01/18/2023]
Affiliation(s)
- Sangwook Lee
- Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, USA
- School of Materials Science and Engineering, Kyungpook National University, Daegu 41566, South Korea
| | - Kedar Hippalgaonkar
- Department of Mechanical Engineering, University of California, Berkeley, CA 94720, USA
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Innovis, 08-03, 138634 Singapore
| | - Fan Yang
- Department of Mechanical Engineering, University of California, Berkeley, CA 94720, USA
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Jiawang Hong
- School of Aerospace Engineering and Institute of Advanced Structure Technology, Beijing Institute of Technology, Beijing 100081, China
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Changhyun Ko
- Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, USA
| | - Joonki Suh
- Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, USA
| | - Kai Liu
- Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, USA
- Materials Sciences Division, LBNL, Berkeley, CA 94720, USA
| | - Kevin Wang
- Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, USA
| | - Jeffrey J. Urban
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Xiang Zhang
- Department of Mechanical Engineering, University of California, Berkeley, CA 94720, USA
- Materials Sciences Division, LBNL, Berkeley, CA 94720, USA
- Department of Physics, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Chris Dames
- Department of Mechanical Engineering, University of California, Berkeley, CA 94720, USA
- Materials Sciences Division, LBNL, Berkeley, CA 94720, USA
| | - Sean A. Hartnoll
- Department of Physics, Stanford University, Stanford, CA 94305, USA
| | - Olivier Delaire
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
- Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC 27708, USA
| | - Junqiao Wu
- Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, USA
- Materials Sciences Division, LBNL, Berkeley, CA 94720, USA
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10
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Shin JF, Niu H, Alaria J, Claridge JB, Rosseinsky MJ. Substitution of Re7+ into CaMnO3: an efficient free electron generation dopant for tuning of thermoelectric properties. Phys Chem Chem Phys 2017; 19:30781-30789. [DOI: 10.1039/c7cp06805k] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Highly dense CaMn1−xRexO3 samples containing heptavalent Re7+ exhibited ZT of 0.16(3) at 947 K, which is comparable to the highest values reported for dense B-site doped CaMnO3.
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Affiliation(s)
- J. Felix Shin
- Department of Chemistry, University of Liverpool
- Liverpool L69 7ZD
- UK
| | - Hongjun Niu
- Department of Chemistry, University of Liverpool
- Liverpool L69 7ZD
- UK
| | - Jonathan Alaria
- Department of Physics, University of Liverpool
- Liverpool L69 7ZE
- UK
| | - John B. Claridge
- Department of Chemistry, University of Liverpool
- Liverpool L69 7ZD
- UK
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11
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Emergence of nontrivial magnetic excitations in a spin-liquid state of kagomé volborthite. Proc Natl Acad Sci U S A 2016; 113:8653-7. [PMID: 27439874 DOI: 10.1073/pnas.1524076113] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
When quantum fluctuations destroy underlying long-range ordered states, novel quantum states emerge. Spin-liquid (SL) states of frustrated quantum antiferromagnets, in which highly correlated spins fluctuate down to very low temperatures, are prominent examples of such quantum states. SL states often exhibit exotic physical properties, but the precise nature of the elementary excitations behind such phenomena remains entirely elusive. Here, we use thermal Hall measurements that can capture the unexplored property of the elementary excitations in SL states, and report the observation of anomalous excitations that may unveil the unique features of the SL state. Our principal finding is a negative thermal Hall conductivity [Formula: see text] which the charge-neutral spin excitations in a gapless SL state of the 2D kagomé insulator volborthite Cu3V2O7(OH)2[Formula: see text]2H2O exhibit, in much the same way in which charged electrons show the conventional electric Hall effect. We find that [Formula: see text] is absent in the high-temperature paramagnetic state and develops upon entering the SL state in accordance with the growth of the short-range spin correlations, demonstrating that [Formula: see text] is a key signature of the elementary excitation formed in the SL state. These results suggest the emergence of nontrivial elementary excitations in the gapless SL state which feel the presence of fictitious magnetic flux, whose effective Lorentz force is found to be less than 1/100 of the force experienced by free electrons.
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12
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Cheng Z, Han M, Yuan P, Xu S, Cola BA, Wang X. Strongly anisotropic thermal and electrical conductivities of a self-assembled silver nanowire network. RSC Adv 2016. [DOI: 10.1039/c6ra20331k] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Self-assembled silver nanowire network shows strongly anisotropic electrical and thermal conduction.
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Affiliation(s)
- Zhe Cheng
- Department of Mechanical Engineering
- 2010 Black Engineering Building
- Iowa State University
- Ames
- USA
| | - Meng Han
- Department of Mechanical Engineering
- 2010 Black Engineering Building
- Iowa State University
- Ames
- USA
| | - Pengyu Yuan
- Department of Mechanical Engineering
- 2010 Black Engineering Building
- Iowa State University
- Ames
- USA
| | - Shen Xu
- Department of Mechanical Engineering
- 2010 Black Engineering Building
- Iowa State University
- Ames
- USA
| | - Baratunde A. Cola
- George W. Woodruff School of Mechanical Engineering
- Georgia Institute of Technology
- Atlanta
- USA
| | - Xinwei Wang
- Department of Mechanical Engineering
- 2010 Black Engineering Building
- Iowa State University
- Ames
- USA
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13
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Temperature dependence of electrical and thermal conduction in single silver nanowire. Sci Rep 2015; 5:10718. [PMID: 26035288 PMCID: PMC4451791 DOI: 10.1038/srep10718] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Accepted: 04/23/2015] [Indexed: 11/16/2022] Open
Abstract
In this work, the thermal and electrical transport in an individual silver nanowire is characterized down to 35 K for in-depth understanding of the strong structural defect induced electron scattering. The results indicate that, at room temperature, the electrical resistivity increases by around 4 folds from that of bulk silver. The Debye temperature (151 K) of the silver nanowire is found 36% lower than that (235 K) of bulk silver, confirming strong phonon softening. At room temperature, the thermal conductivity is reduced by 55% from that of bulk silver. This reduction becomes larger as the temperature goes down. To explain the opposite trends of thermal conductivity (κ) ~ temperature (T) of silver nanowire and bulk silver, a unified thermal resistivity () is used to elucidate the electron scattering mechanism. A large residual Θ is observed for silver nanowire while that of the bulk silver is almost zero. The same ~T trend proposes that the silver nanowire and bulk silver share the similar phonon-electron scattering mechanism for thermal transport. Due to phonon-assisted electron energy transfer across grain boundaries, the Lorenz number of the silver nanowire is found much larger than that of bulk silver and decreases with decreasing temperature.
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14
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Xu EZ, Li Z, Martinez JA, Sinitsyn N, Htoon H, Li N, Swartzentruber B, Hollingsworth JA, Wang J, Zhang SX. Diameter dependent thermoelectric properties of individual SnTe nanowires. NANOSCALE 2015; 7:2869-2876. [PMID: 25623253 DOI: 10.1039/c4nr05870d] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The lead-free compound tin telluride (SnTe) has recently been suggested to be a promising thermoelectric material. In this work, we report on the first thermoelectric study of individual single-crystalline SnTe nanowires with different diameters ranging from ∼218 to ∼913 nm. Measurements of thermopower S, electrical conductivity σ and thermal conductivity κ were carried out on the same nanowires over a temperature range of 25-300 K. While the electrical conductivity does not show a strong diameter dependence, the thermopower increases by a factor of two when the nanowire diameter is decreased from ∼913 nm to ∼218 nm. The thermal conductivity of the measured NWs is lower than that of the bulk SnTe, which may arise from the enhanced phonon - surface boundary scattering and phonon-defect scattering. Temperature dependent figure of merit ZT was determined for individual nanowires and the achieved maximum value at room temperature is about three times higher than that in bulk samples of comparable carrier density.
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Affiliation(s)
- E Z Xu
- Department of Physics, Indiana University, Bloomington, Indiana 47405, USA.
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15
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The Wiedemann-Franz law in the putative one-dimensional metallic phase of PrBa₂Cu₄O₈. Sci Rep 2013; 3:3261. [PMID: 24253025 PMCID: PMC3834867 DOI: 10.1038/srep03261] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 10/28/2013] [Indexed: 11/28/2022] Open
Abstract
The nature of the electronic state of a metal depends strongly on its dimensionality. In a system of isolated conducting chains, the Fermi-liquid (quasiparticle) description appropriate for higher dimensions is replaced by the so-called Tomonaga-Luttinger liquid picture characterized by collective excitations of spin and charge. Temperature is often regarded as a viable tuning parameter between states of different dimensionality, but what happens once thermal broadening becomes comparable to the interchain hopping energy remains an unresolved issue, one that is central to many organic and inorganic conductors. Here we use the ratio of the thermal to electrical conductivities to probe the nature of the electronic state in PrBa2Cu4O8 as a function of temperature. We find that despite the interchain transport becoming non-metallic, the charge carriers within the CuO chains appear to retain their quasiparticle nature. This implies that temperature alone cannot induce a crossover from Fermi-liquid to Tomonaga-Luttinger-liquid behaviour in quasi-one-dimensional metals.
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16
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Wakeham N, Bangura AF, Xu X, Mercure JF, Greenblatt M, Hussey NE. Gross violation of the Wiedemann-Franz law in a quasi-one-dimensional conductor. Nat Commun 2011; 2:396. [PMID: 21772267 PMCID: PMC3144592 DOI: 10.1038/ncomms1406] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Accepted: 06/20/2011] [Indexed: 11/09/2022] Open
Abstract
When charge carriers are spatially confined to one dimension, conventional Fermi-liquid theory breaks down. In such Tomonaga-Luttinger liquids, quasiparticles are replaced by distinct collective excitations of spin and charge that propagate independently with different velocities. Although evidence for spin-charge separation exists, no bulk low-energy probe has yet been able to distinguish successfully between Tomonaga-Luttinger and Fermi-liquid physics. Here we show experimentally that the ratio of the thermal and electrical Hall conductivities in the metallic phase of quasi-one-dimensional Li(0.9)Mo(6)O(17) diverges with decreasing temperature, reaching a value five orders of magnitude larger than that found in conventional metals. Both the temperature dependence and magnitude of this ratio are consistent with Tomonaga-Luttinger liquid theory. Such a dramatic manifestation of spin-charge separation in a bulk three-dimensional solid offers a unique opportunity to explore how the fermionic quasiparticle picture recovers, and over what time scale, when coupling to a second or third dimension is restored.
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Affiliation(s)
- Nicholas Wakeham
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK
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17
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Alexandrov AS. Diamagnetism of real-space pairs above T(c) in hole doped cuprates. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:426004. [PMID: 21403318 DOI: 10.1088/0953-8984/22/42/426004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The nonlinear normal state diamagnetism reported by Li et al (2010 Phys. Rev. B 81 054510) is shown to be incompatible with a claimed Cooper pairing and vortex liquid above the resistive critical temperature. However, it is perfectly compatible with the normal state Landau diamagnetism of real-space composed bosons, which provides a description of the nonlinear magnetization curves of the less anisotropic cuprates La-Sr-Cu-O (LSCO) and Y-Ba-Cu-O (YBCO) as well as for strongly anisotropic bismuth-based cuprates over the whole range of available magnetic fields.
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Affiliation(s)
- A S Alexandrov
- Department of Physics, Loughborough University, Loughborough, UK
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18
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Onose Y, Shiomi Y, Tokura Y. Lorenz number determination of the dissipationless nature of the anomalous Hall effect in itinerant ferromagnets. PHYSICAL REVIEW LETTERS 2008; 100:016601. [PMID: 18232797 DOI: 10.1103/physrevlett.100.016601] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2007] [Indexed: 05/25/2023]
Abstract
We have measured the thermal Hall conductivity for ferromagnetic Ni and Ni0.97Cu0.03. In the low temperature region ( less, similar 100 K), we show for the first time that the Wiedemann-Franz law is satisfied even for the anomalous Hall current. While the Hall Lorenz number for the normal part decreases rapidly with temperature, that for the anomalous part shows much less deviation from the free-electron Lorenz number. This evidences the dissipationless nature of the anomalous Hall effect.
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Affiliation(s)
- Y Onose
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
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Sharma PA, Harrison N, Jaime M, Oh YS, Kim KH, Batista CD, Amitsuka H, Mydosh JA. Phonon thermal transport of URu2Si2: broken translational symmetry and strong-coupling of the "hidden order" to the lattice. PHYSICAL REVIEW LETTERS 2006; 97:156401. [PMID: 17155346 DOI: 10.1103/physrevlett.97.156401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2005] [Indexed: 05/12/2023]
Abstract
A dramatic increase in the total thermal conductivity (kappa) is observed in the hidden order (HO) state of single crystal URu2Si2. Through measurements of the thermal Hall conductivity, we explicitly show that the electronic contribution to kappa is extremely small, so that this large increase in kappa is dominated by phonon conduction. An itinerant BCS or mean-field model describes this behavior well: the increase in kappa is associated with the opening of a large energy gap at the Fermi surface, thereby decreasing electron-phonon scattering. Our analysis implies that the "hidden order" parameter is strongly coupled to the lattice, suggestive of a broken symmetry involving charge degrees of freedom.
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Affiliation(s)
- P A Sharma
- National High Magnetic Field Laboratory, Los Alamos National Laboratory, MS E536, Los Alamos, New Mexico 87545, USA
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20
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Edwards PP, Rao CNR, Kumar N, Alexandrov AS. The Possibility of a Liquid Superconductor. Chemphyschem 2006; 7:2015-21. [PMID: 16892477 DOI: 10.1002/cphc.200600241] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
All superconductors are solids in their superconducting state, this canonical electronic state of matter presently having only been observed well below the melting temperature of the solid. The discovery of high-temperature superconductivity in cuprates has widened significantly our horizons of the theoretical understanding of the physical phenomenon. A number of observations point to the possibility that superconductors with a high superconducting transition temperature may not be conventional Bardeen-Cooper-Schrieffer (BCS) superconductors, but rather derive from the Bose-Einstein condensation of real-space pairs. While BCS superconductors exist in the solid state (probably with the exception of metallic liquid hydrogen at ultrahigh pressures), we argue here that a superconducting charged Bose liquid may be found in a true liquid state of condensed matter at ambient pressure. An experimental scenario is outlined in fluid metal-ammonia solutions for stabilizing and observing a high-temperature superconducting liquid (ca. 230 K) or at least a vitreous superconductor in the corresponding quenched solutions (ca. 160 K).
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Affiliation(s)
- Peter P Edwards
- Inorganic Chemistry Laboratory, University of Oxford South Parks Road, Oxford OX1 3QR, UK.
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21
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Behnia K, Bel R, Kasahara Y, Nakajima Y, Jin H, Aubin H, Izawa K, Matsuda Y, Flouquet J, Haga Y, Onuki Y, Lejay P. Thermal transport in the hidden-order state of URu2Si2. PHYSICAL REVIEW LETTERS 2005; 94:156405. [PMID: 15904167 DOI: 10.1103/physrevlett.94.156405] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2004] [Indexed: 05/02/2023]
Abstract
We present a study of thermal conductivity in the normal state of the heavy-fermion superconductor URu2Si2. Ordering at 18 K leads to a steep increase in thermal conductivity and (in contrast with all other cases of magnetic ordering in heavy-fermion compounds) to an enhancement of the Lorenz number. By linking this observation to several other previously reported features, we conclude that most of the carriers disappear in the ordered state and this leads to a drastic increase in both the phononic and electronic mean free path.
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Affiliation(s)
- K Behnia
- Laboratoire de Physique Quantique (CNRS), ESPCI, 10 Rue de Vauquelin, 75231 Paris, France
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22
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Lee KK, Alexandrov AS, Liang WY. Lorenz number in high T(c) superconductors: evidence for bipolarons. PHYSICAL REVIEW LETTERS 2003; 90:217001. [PMID: 12786580 DOI: 10.1103/physrevlett.90.217001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2002] [Indexed: 05/24/2023]
Abstract
The strong electron-phonon interaction in cuprates has gathered support over the last decade in a number of experiments. While phonons remain almost unrenormalized, electrons are transformed into itinerant bipolarons and thermally excited polarons when the electron-phonon interaction is strong. We calculate the Lorenz number of the system to show that the Wiedemann-Franz law breaks down because of the interference of polaron and bipolaron contributions in the heat flow. The model fits numerically the experimental Hall Lorenz number, which provides direct evidence for bipolarons in the cuprates.
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Affiliation(s)
- K K Lee
- IRC in Superconductivity, Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, United Kingdom
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23
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Khveshchenko DV, Paaske J. Incipient nodal pairing in planar d-wave superconductors. PHYSICAL REVIEW LETTERS 2001; 86:4672-4675. [PMID: 11384311 DOI: 10.1103/physrevlett.86.4672] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2000] [Indexed: 05/23/2023]
Abstract
The possibility of a second pairing transition d --> d + is ( d + id') in planar d-wave superconductors which occurs in the absence of external magnetic field, magnetic impurities, or boundaries is established in the framework of the nonperturbative phenomenon of dynamical chiral symmetry breaking in the system of (2+1)-dimensional Dirac-like nodal quasiparticles. We determine the critical exponents and quasiparticle spectral functions that characterize the corresponding quantum-critical behavior and discuss some of its potentially observable spectral and transport features.
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Affiliation(s)
- D V Khveshchenko
- Department of Physics and Astronomy, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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Zhang Y, Ong NP, Anderson PW, Bonn DA, Liang R, Hardy WN. Giant enhancement of the thermal Hall conductivity kappa(xy) in the superconductor YBa(2)Cu(3)O(7). PHYSICAL REVIEW LETTERS 2001; 86:890-893. [PMID: 11177966 DOI: 10.1103/physrevlett.86.890] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2000] [Indexed: 05/23/2023]
Abstract
In high-purity YBa(2)Cu(3)O(7), the (weak-field) thermal Hall conductivity kappa(xy) is observed to increase a thousand-fold between 90 and 30 K. The inferred quasiparticle lifetime tau increases a hundred-fold starting below 90 K, in disagreement with a recent photoemission experiment. We show that kappa(xy) exhibits a specific scaling behavior below approximately 30 K. This scaling may bear on the issue of whether Landau quantization of the quasiparticle states occurs.
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Affiliation(s)
- Y Zhang
- Joseph Henry Laboratories of Physics, Princeton University, New Jersey 08544, USA
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