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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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Ni JM, Huang YY, Cheng EJ, Yu YJ, Pan BL, Li Q, Xu LM, Tian ZM, Li SY. Giant isotropic magneto-thermal conductivity of metallic spin liquid candidate Pr 2Ir 2O 7 with quantum criticality. Nat Commun 2021; 12:307. [PMID: 33436565 PMCID: PMC7804409 DOI: 10.1038/s41467-020-20562-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 12/09/2020] [Indexed: 12/05/2022] Open
Abstract
Spin liquids are exotic states with no spontaneous symmetry breaking down to zero-temperature because of the highly entangled and fluctuating spins in frustrated systems. Exotic excitations like magnetic monopoles, visons, and photons may emerge from quantum spin ice states, a special kind of spin liquids in pyrochlore lattices. These materials usually are insulators, with an exception of the pyrochlore iridate Pr2Ir2O7, which was proposed as a metallic spin liquid located at a zero-field quantum critical point. Here we report the ultralow-temperature thermal conductivity measurements on Pr2Ir2O7. The Wiedemann-Franz law is verified at high fields and inferred at zero field, suggesting no breakdown of Landau quasiparticles at the quantum critical point, and the absence of mobile fermionic excitations. This result puts strong constraints on the description of the quantum criticality in Pr2Ir2O7. Unexpectedly, although the specific heats are anisotropic with respect to magnetic field directions, the thermal conductivities display the giant but isotropic response. This indicates that quadrupolar interactions and quantum fluctuations are important, which will help determine the true ground state of this material.
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Affiliation(s)
- J M Ni
- State Key Laboratory of Surface Physics, Department of Physics, and Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, China
| | - Y Y Huang
- State Key Laboratory of Surface Physics, Department of Physics, and Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, China
| | - E J Cheng
- State Key Laboratory of Surface Physics, Department of Physics, and Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, China
| | - Y J Yu
- State Key Laboratory of Surface Physics, Department of Physics, and Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, China
| | - B L Pan
- State Key Laboratory of Surface Physics, Department of Physics, and Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, China
| | - Q Li
- State Key Laboratory of Surface Physics, Department of Physics, and Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, China
| | - L M Xu
- School of Physics, and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Z M Tian
- School of Physics, and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, China.
| | - S Y Li
- State Key Laboratory of Surface Physics, Department of Physics, and Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, China.
- Collaborative Innovation Center of Advanced Microstructures, Nanjing, 210093, China.
- Shanghai Research Center for Quantum Sciences, Shanghai, 201315, China.
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Liang X, Dai F. Reduction of the Lorenz Number in Copper at Room Temperature due to Strong Inelastic Electron Scattering Brought about by High-Density Dislocations. J Phys Chem Lett 2019; 10:507-512. [PMID: 30645128 DOI: 10.1021/acs.jpclett.8b03544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In this work, heat and charge transport were measured in a series of deformed bulk Cu samples where dislocation density was tuned but dislocation character generally remained unchanged. We observed a notable violation of the Wiedemann-Franz law at room temperature for such a conventional metal. We show that high-density dislocations introduce strong inelastic electron scattering, which relax heat and charge currents to different extents. A reduction of Lorenz number by 15% was observed. We reveal that the contribution from elastic scattering to the incremental thermal resistivity scarcely varies with dislocation density, but the contribution due to inelastic scattering monotonically increases and becomes overwhelmingly dominant for dislocation density above 1.0 × 1015 m-2.
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Affiliation(s)
- Xin Liang
- School of Materials Science and Engineering , Changzhou University , Changzhou , Jiangsu 213164 , China
| | - Feihu Dai
- School of Materials Science and Engineering , Changzhou University , Changzhou , Jiangsu 213164 , China
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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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Gegenwart P. Grüneisen parameter studies on heavy fermion quantum criticality. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2016; 79:114502. [PMID: 27710924 DOI: 10.1088/0034-4885/79/11/114502] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The Grüneisen parameter, experimentally determined from the ratio of thermal expansion to specific heat, quantifies the pressure dependence of characteristic energy scales of matter. It is highly enhanced for Kondo lattice systems, whose properties are strongly dependent on the pressure sensitive antiferromagnetic exchange interaction between f- and conduction electrons. In this review, we focus on the divergence of the Grüneisen parameter and its magnetic analogue, the adiabatic magnetocaloric effect, for heavy-fermion metals near quantum critical points. We compare experimental results with current theoretical models, including the effect of strong geometrical frustration. We also discuss the possibility of using materials with the divergent magnetic Grüneisen parameter for adiabatic demagnetization cooling to very low temperatures.
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Affiliation(s)
- Philipp Gegenwart
- EP VI, Center for Electronic Correlations and Magnetism, Institute of Physics, Augsburg University, 86159 Augsburg, Germany
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Pixley JH, Yu R, Si Q. Quantum phases of the Shastry-Sutherland Kondo lattice: implications for the global phase diagram of heavy-fermion metals. PHYSICAL REVIEW LETTERS 2014; 113:176402. [PMID: 25379926 DOI: 10.1103/physrevlett.113.176402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Indexed: 06/04/2023]
Abstract
Considerable recent theoretical and experimental effort has been devoted to the study of quantum criticality and novel phases of antiferromagnetic heavy-fermion metals. In particular, quantum phase transitions have been discovered in heavy-fermion compounds with geometrical frustration. These developments have motivated us to study the competition between the Ruderman-Kittel-Kasuya-Yosida and Kondo interactions on the Shastry-Sutherland lattice. We determine the zero-temperature phase diagram as a function of magnetic frustration and Kondo coupling within a slave-fermion approach. Pertinent phases include the valence bond solid and heavy Fermi liquid. In the presence of antiferromagnetic order, our zero-temperature phase diagram is remarkably similar to the global phase diagram proposed earlier based on general grounds. We discuss the implications of our results for the experiments on Yb2Pt2Pb and related compounds.
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Affiliation(s)
- J H Pixley
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - Rong Yu
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA and Department of Physics and Beijing Key Laboratory of Opto-Electronic Functional Materials and Micro-Nano Devices, Renmin University of China, Beijing 100872, China
| | - Qimiao Si
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
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Tokiwa Y, Garst M, Gegenwart P, Bud'ko SL, Canfield PC. Quantum bicriticality in the heavy-fermion metamagnet YbAgGe. PHYSICAL REVIEW LETTERS 2013; 111:116401. [PMID: 24074108 DOI: 10.1103/physrevlett.111.116401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Indexed: 06/02/2023]
Abstract
Bicritical points, at which two distinct symmetry-broken phases become simultaneously unstable, are typical for spin-flop metamagnetism. Interestingly, the heavy-fermion compound YbAgGe also possesses such a bicritical point (BCP) with a low temperature T(BCP)≈0.3 K at a magnetic field of μH(BCP)≈4.5 T. In its vicinity, YbAgGe exhibits anomalous behavior that we attribute to the influence of a quantum bicritical point that is close in parameter space yet can be reached by tuning T(BCP) further to zero. Using high-resolution measurements of the magnetocaloric effect, we demonstrate that the magnetic Grüneisen parameter ΓH indeed both changes sign and diverges as required for quantum criticality. Moreover, ΓH displays a characteristic scaling behavior but only on the low-field side H≲H(BCP), indicating a pronounced asymmetry with respect to the critical field. We speculate that the small value of T(BCP) is related to the geometric frustration of the Kondo lattice of YbAgGe.
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Affiliation(s)
- Y Tokiwa
- I. Physikalisches Institut, Georg-August-Universität Göttingen, 37077 Göttingen, Germany
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