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Ouyang W, Lygo AC, Chen Y, Zheng H, Vu D, Wooten BL, Liang X, Heremans JP, Stemmer S, Liao B. Extraordinary Thermoelectric Properties of Topological Surface States in Quantum-Confined Cd 3As 2 Thin Films. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2311644. [PMID: 38684220 DOI: 10.1002/adma.202311644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Revised: 03/23/2024] [Indexed: 05/02/2024]
Abstract
Topological insulators and semimetals have been shown to possess intriguing thermoelectric properties promising for energy harvesting and cooling applications. However, thermoelectric transport associated with the Fermi arc topological surface states on topological Dirac semimetals remains less explored. This work systematically examines thermoelectric transport in a series of topological Dirac semimetal Cd3As2 thin films grown by molecular beam epitaxy. Surprisingly, significantly enhanced Seebeck effect and anomalous Nernst effect are found at cryogenic temperatures when the Cd3As2 layer is thin. In particular, a peak Seebeck coefficient of nearly 500 µV K-1 and a corresponding thermoelectric power factor over 30 mW K-2 m-1 are observed at 5 K in a 25-nm-thick sample. Combining angle-dependent quantum oscillation analysis, magnetothermoelectric measurement, transport modeling, and first-principles simulation, the contributions from bulk and surface conducting channels are isolated and the unusual thermoelectric properties are attributed to the topological surface states. The analysis showcases the rich thermoelectric transport physics in quantum-confined topological Dirac semimetal thin films and suggests new routes to achieving high thermoelectric performance at cryogenic temperatures.
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Affiliation(s)
- Wenkai Ouyang
- Department of Mechanical Engineering, University of California, Santa Barbara, CA, 93106, USA
| | - Alexander C Lygo
- Materials Department, University of California, Santa Barbara, CA, 93106, USA
| | - Yubi Chen
- Department of Mechanical Engineering, University of California, Santa Barbara, CA, 93106, USA
| | - Huiyuan Zheng
- Department of Physics, University of Hong Kong, Hong Kong, 999077, China
| | - Dung Vu
- Department of Mechanical and Aerospace Engineering, Ohio State University, Columbus, OH, 43210, USA
| | - Brandi L Wooten
- Department of Mechanical and Aerospace Engineering, Ohio State University, Columbus, OH, 43210, USA
| | - Xichen Liang
- Department of Mechanical Engineering, University of California, Santa Barbara, CA, 93106, USA
| | - Joseph P Heremans
- Department of Mechanical and Aerospace Engineering, Ohio State University, Columbus, OH, 43210, USA
| | - Susanne Stemmer
- Materials Department, University of California, Santa Barbara, CA, 93106, USA
| | - Bolin Liao
- Department of Mechanical Engineering, University of California, Santa Barbara, CA, 93106, USA
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Hwang J, Ruan W, Chen Y, Tang S, Crommie MF, Shen ZX, Mo SK. Charge density waves in two-dimensional transition metal dichalcogenides. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2024; 87:044502. [PMID: 38518359 DOI: 10.1088/1361-6633/ad36d3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 03/22/2024] [Indexed: 03/24/2024]
Abstract
Charge density wave (CDW is one of the most ubiquitous electronic orders in quantum materials. While the essential ingredients of CDW order have been extensively studied, a comprehensive microscopic understanding is yet to be reached. Recent research efforts on the CDW phenomena in two-dimensional (2D) materials provide a new pathway toward a deeper understanding of its complexity. This review provides an overview of the CDW orders in 2D with atomically thin transition metal dichalcogenides (TMDCs) as the materials platform. We mainly focus on the electronic structure investigations on the epitaxially grown TMDC samples with angle-resolved photoemission spectroscopy and scanning tunneling microscopy/spectroscopy as complementary experimental tools. We discuss the possible origins of the 2D CDW, novel quantum states coexisting with them, and exotic types of charge orders that can only be realized in the 2D limit.
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Affiliation(s)
- Jinwoong Hwang
- Department of Physics and Institute of Quantum Convergence Technology, Kangwon National University, Chuncheon 24341, Republic of Korea
| | - Wei Ruan
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200438, People's Republic of China
| | - Yi Chen
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, People's Republic of China
- Interdisciplinary Institute of Light-Element Quantum Materials and Research Center for Light-Element Advanced Materials, Peking University, Beijing 100871, People's Republic of China
| | - Shujie Tang
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China
| | - Michael F Crommie
- Department of Physics, University of California, Berkeley, CA, United States of America
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States of America
- Kavli Energy NanoSciences Institute at the University of California at Berkeley, Berkeley, CA 94720, United States of America
| | - Zhi-Xun Shen
- Geballe Laboratory for Advanced Materials, Departments of Physics and Applied Physics, Stanford University, Stanford, CA, United States of America
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, United States of America
| | - Sung-Kwan Mo
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 United States of America
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Andriushin ND, Sukhanov AS, Korshunov AN, Pavlovskii MS, Rahn MC, Nikitin SE. Phonon Topology and Winding of Spectral Weight in Graphite. PHYSICAL REVIEW LETTERS 2023; 131:246601. [PMID: 38181154 DOI: 10.1103/physrevlett.131.246601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 10/19/2023] [Indexed: 01/07/2024]
Abstract
The topology of electronic and phonon band structures of graphene is well studied and known to exhibit a Dirac cone at the K point of the Brillouin zone. Here, we applied inelastic x-ray scattering (IXS) along with ab initio calculations to investigate phonon topology in graphite, the 3D analog of graphene. We identified a pair of modes that form a very weakly gapped linear anticrossing at the K point that can be essentially viewed as a Dirac cone approximant. The IXS intensity in the vicinity of the quasi-Dirac point reveals a harmonic modulation of the phonon spectral weight above and below the Dirac energy, which was previously proposed as an experimental fingerprint of the nontrivial topology. We illustrate how the topological winding of IXS intensity can be understood in terms of atomic displacements and highlight that the intensity winding is not in fact sensitive in telling quasi- and true Dirac points apart.
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Affiliation(s)
- N D Andriushin
- Institut für Festkörper- und Materialphysik, Technische Universität Dresden, D-01069 Dresden, Germany
| | - A S Sukhanov
- Institut für Festkörper- und Materialphysik, Technische Universität Dresden, D-01069 Dresden, Germany
| | - A N Korshunov
- Institut für Festkörper- und Materialphysik, Technische Universität Dresden, D-01069 Dresden, Germany
- Kirensky Institute of Physics, Siberian Branch, Russian Academy of Sciences, Krasnoyarsk 660036, Russian Federation
- Quantum Criticality and Dynamics Group, Paul Scherrer Institut, CH-5232 Villigen-PSI, Switzerland
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, CH-5232 Villigen-PSI, Switzerland
| | - M S Pavlovskii
- Kirensky Institute of Physics, Siberian Branch, Russian Academy of Sciences, Krasnoyarsk 660036, Russian Federation
| | - M C Rahn
- Institut für Festkörper- und Materialphysik, Technische Universität Dresden, D-01069 Dresden, Germany
| | - S E Nikitin
- Quantum Criticality and Dynamics Group, Paul Scherrer Institut, CH-5232 Villigen-PSI, Switzerland
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, CH-5232 Villigen-PSI, Switzerland
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4
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Giant Phonon Anomaly in Topological Nodal-Line Semimetals. FUNDAMENTAL RESEARCH 2022. [DOI: 10.1016/j.fmre.2022.12.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
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5
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Ghim M, Jhi SH. Kohn anomalies in topological insulator thin films: first-principles study. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:265002. [PMID: 35405670 DOI: 10.1088/1361-648x/ac664a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 04/11/2022] [Indexed: 06/14/2023]
Abstract
Kohn anomaly is a non-smooth phonon softening induced by electron-phonon coupling in low-dimensional metals. Some measurements claimed that Kohn anomalies are present in topological materials due to the Dirac fermions in the bulk or in the surface. However, first-principles calculations have not reproduced the Kohn anomalies, especially, on the surface of topological insulators. It is still unclear about the origin of the controversy for the existence of the Kohn anomaly whether it is a numerical shortcoming or misinterpretation in measurement. In this study, we investigate the surface Kohn anomaly in two topological insulators Bi2Se3and SnSe using the state-of-the-art Wannier interpolation schemes. We find that Bi2Se3exhibits the Kohn anomaly but only in the bulk-like phonon modes by structural confinement along thec-axis. Interestingly, SnSe exhibits the surface Kohn anomaly in support of the experimental report on Pb0.7Sn0.3Se. We show that double Dirac cones in SnSe surface states are responsible for the Kohn anomaly, which is even enhanced if the subsurface states are partially occupied.
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Affiliation(s)
- Minjae Ghim
- Department of Physics, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
| | - Seung-Hoon Jhi
- Department of Physics, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
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Roy AP, Bajaj N, Mittal R, Babu PD, Bansal D. Quasi-One-Dimensional Fermi Surface Nesting and Hidden Nesting Enable Multiple Kohn Anomalies in α-Uranium. PHYSICAL REVIEW LETTERS 2021; 126:096401. [PMID: 33750153 DOI: 10.1103/physrevlett.126.096401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Revised: 01/20/2021] [Accepted: 01/22/2021] [Indexed: 06/12/2023]
Abstract
The topology of the Fermi surface controls the electronic response of a metal, including charge density wave (CDW) formation. A topology conducive for Fermi surface nesting (FSN) allows the electronic susceptibility χ_{0} to diverge and induce a CDW at wave vector q_{CDW}. Kohn extended the implications of FSN to show that the imaginary part of the lattice dynamical susceptibility χ_{L}^{''} also responds anomalously for all phonon branches at q_{CDW}-a phenomenon referred to as the Kohn anomaly. However, materials exhibiting multiple Kohn anomalies remain rare. Using first-principles simulations of χ_{0} and χ_{L}^{''}, and previous scattering measurements [Crummett et al., Phys. Rev. B 19, 6028 234 (1979)PRBMDO0163-1829], we show that α-uranium harbors multiple Kohn anomalies enabled by the combined effect of FSN and "hidden" nesting, i.e., nesting of electronic states above and below the Fermi surface. FSN and hidden nesting lead to a ridgelike feature in the real part of χ_{0}, allowing interatomic forces to modulate strongly and multiple Kohn anomalies to emerge. These results emphasize the importance of hidden nesting in controlling χ_{0} and χ_{L}^{''} to exploit electronic and lattice states and enable engineering of advanced materials, including topological Weyl semimetals and superconductors.
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Affiliation(s)
- Aditya Prasad Roy
- Department of Mechanical Engineering, Indian Institute of Technology Bombay, Mumbai, MH 400076, India
| | - Naini Bajaj
- Department of Mechanical Engineering, Indian Institute of Technology Bombay, Mumbai, MH 400076, India
| | - Ranjan Mittal
- Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai, MH 400085, India
- Homi Bhabha National Institute, Anushaktinagar, Mumbai, MH 400094, India
| | - Peram D Babu
- UGC-DAE Consortium for Scientific Research, Mumbai Centre, R5-Shed, BARC, Trombay, Mumbai, MH 400085, India
| | - Dipanshu Bansal
- Department of Mechanical Engineering, Indian Institute of Technology Bombay, Mumbai, MH 400076, India
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Xie F, Ren M, Wu W, Yu D, Cai W, Xu J. Phase-Transition Optical Activity in Chiral Metamaterials. PHYSICAL REVIEW LETTERS 2020; 125:237401. [PMID: 33337210 DOI: 10.1103/physrevlett.125.237401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 09/29/2020] [Indexed: 06/12/2023]
Abstract
Optical activity from chiral metamaterials is both fundamental in electrodynamics and useful for polarization control applications. It is normally expected that due to infinitesimally small thickness, two-dimensional (2D) planar metamaterials cannot introduce large optical rotations. Here, we present a new mechanism to achieve strong optical rotation up to 90° by evoking phase transition in the 2D metamaterials through tuning coupling strength between meta-atoms. We analytically elucidate such phenomenon by developing a model of phase-transition coupled-oscillator array. And we further corroborate our ideas with both numerical simulations and experiments. Our findings would pave a new way for applying the concept of phase transition in photonics for designing novel optical devices for strong polarization controls and other novel applications.
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Affiliation(s)
- Fei Xie
- The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of Physics and TEDA Applied Physics Institute, Nankai University, Tianjin 300071, People's Republic of China
| | - Mengxin Ren
- The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of Physics and TEDA Applied Physics Institute, Nankai University, Tianjin 300071, People's Republic of China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, People's Republic of China
| | - Wei Wu
- The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of Physics and TEDA Applied Physics Institute, Nankai University, Tianjin 300071, People's Republic of China
| | - Dianqiang Yu
- The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of Physics and TEDA Applied Physics Institute, Nankai University, Tianjin 300071, People's Republic of China
| | - Wei Cai
- The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of Physics and TEDA Applied Physics Institute, Nankai University, Tianjin 300071, People's Republic of China
| | - Jingjun Xu
- The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of Physics and TEDA Applied Physics Institute, Nankai University, Tianjin 300071, People's Republic of China
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Nguyen T, Han F, Andrejevic N, Pablo-Pedro R, Apte A, Tsurimaki Y, Ding Z, Zhang K, Alatas A, Alp EE, Chi S, Fernandez-Baca J, Matsuda M, Tennant DA, Zhao Y, Xu Z, Lynn JW, Huang S, Li M. Topological Singularity Induced Chiral Kohn Anomaly in a Weyl Semimetal. PHYSICAL REVIEW LETTERS 2020; 124:236401. [PMID: 32603171 PMCID: PMC7935413 DOI: 10.1103/physrevlett.124.236401] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 05/13/2020] [Indexed: 06/11/2023]
Abstract
The electron-phonon interaction (EPI) is instrumental in a wide variety of phenomena in solid-state physics, such as electrical resistivity in metals, carrier mobility, optical transition, and polaron effects in semiconductors, lifetime of hot carriers, transition temperature in BCS superconductors, and even spin relaxation in diamond nitrogen-vacancy centers for quantum information processing. However, due to the weak EPI strength, most phenomena have focused on electronic properties rather than on phonon properties. One prominent exception is the Kohn anomaly, where phonon softening can emerge when the phonon wave vector nests the Fermi surface of metals. Here we report a new class of Kohn anomaly in a topological Weyl semimetal (WSM), predicted by field-theoretical calculations, and experimentally observed through inelastic x-ray and neutron scattering on WSM tantalum phosphide. Compared to the conventional Kohn anomaly, the Fermi surface in a WSM exhibits multiple topological singularities of Weyl nodes, leading to a distinct nesting condition with chiral selection, a power-law divergence, and non-negligible dynamical effects. Our work brings the concept of the Kohn anomaly into WSMs and sheds light on elucidating the EPI mechanism in emergent topological materials.
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Affiliation(s)
- Thanh Nguyen
- Department of Nuclear Science and Engineering, MIT, Cambridge, Massachusetts 02139, USA
| | - Fei Han
- Department of Nuclear Science and Engineering, MIT, Cambridge, Massachusetts 02139, USA
| | - Nina Andrejevic
- Department of Materials Science and Engineering, MIT, Cambridge, Massachusetts 02139, USA
| | - Ricardo Pablo-Pedro
- Department of Nuclear Science and Engineering, MIT, Cambridge, Massachusetts 02139, USA
| | - Anuj Apte
- Department of Physics, MIT, Cambridge, Massachusetts 02139, USA
| | - Yoichiro Tsurimaki
- Department of Mechanical Engineering, MIT, Cambridge, Massachusetts 02139, USA
| | - Zhiwei Ding
- Department of Materials Science and Engineering, MIT, Cambridge, Massachusetts 02139, USA
| | - Kunyan Zhang
- Department of Electrical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Ahmet Alatas
- Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Ercan E. Alp
- Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Songxue Chi
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Jaime Fernandez-Baca
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Masaaki Matsuda
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - David Alan Tennant
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Yang Zhao
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
- Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, USA
| | - Zhijun Xu
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
- Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, USA
| | - Jeffrey W. Lynn
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Shengxi Huang
- Department of Electrical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Mingda Li
- Department of Nuclear Science and Engineering, MIT, Cambridge, Massachusetts 02139, USA
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