1
|
Wang L, Zhu J, Chen H, Wang H, Liu J, Huang YX, Jiang B, Zhao J, Shi H, Tian G, Wang H, Yao Y, Yu D, Wang Z, Xiao C, Yang SA, Wu X. Orbital Magneto-Nonlinear Anomalous Hall Effect in Kagome Magnet Fe_{3}Sn_{2}. Phys Rev Lett 2024; 132:106601. [PMID: 38518320 DOI: 10.1103/physrevlett.132.106601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 11/14/2023] [Accepted: 12/20/2023] [Indexed: 03/24/2024]
Abstract
It has been theoretically predicted that perturbation of the Berry curvature by electromagnetic fields gives rise to intrinsic nonlinear anomalous Hall effects that are independent of scattering. Two types of nonlinear anomalous Hall effects are expected. The electric nonlinear Hall effect has recently begun to receive attention, while very few studies are concerned with the magneto-nonlinear Hall effect. Here, we combine experiment and first-principles calculations to show that the kagome ferromagnet Fe_{3}Sn_{2} displays such a magneto-nonlinear Hall effect. By systematic field angular and temperature-dependent transport measurements, we unambiguously identify a large anomalous Hall current that is linear in both applied in-plane electric and magnetic fields, utilizing a unique in-plane configuration. We clarify its dominant orbital origin and connect it to the magneto-nonlinear Hall effect. The effect is governed by the intrinsic quantum geometric properties of Bloch electrons. Our results demonstrate the significance of the quantum geometry of electron wave functions from the orbital degree of freedom and open up a new direction in Hall transport effects.
Collapse
Affiliation(s)
- Lujunyu Wang
- State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, Frontiers Science Center for Nano-optoelectronics, Peking University, Beijing 100871, China
| | - Jiaojiao Zhu
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Haiyun Chen
- State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, Frontiers Science Center for Nano-optoelectronics, Peking University, Beijing 100871, China
| | - Hui Wang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Jinjin Liu
- Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing 100081, China
| | - Yue-Xin Huang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
- School of Sciences, Great Bay University, Dongguan 523000, China
| | - Bingyan Jiang
- State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, Frontiers Science Center for Nano-optoelectronics, Peking University, Beijing 100871, China
| | - Jiaji Zhao
- State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, Frontiers Science Center for Nano-optoelectronics, Peking University, Beijing 100871, China
| | - Hengjie Shi
- State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, Frontiers Science Center for Nano-optoelectronics, Peking University, Beijing 100871, China
| | - Guang Tian
- State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, Frontiers Science Center for Nano-optoelectronics, Peking University, Beijing 100871, China
| | - Haoyu Wang
- State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, Frontiers Science Center for Nano-optoelectronics, Peking University, Beijing 100871, China
| | - Yugui Yao
- Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing 100081, China
- Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems, Beijing Institute of Technology, Beijing 100081, China
- Material Science Center, Yangtze Delta Region Academy of Beijing Institute of Technology, Jiaxing, China
| | - Dapeng Yu
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Zhiwei Wang
- Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing 100081, China
- Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems, Beijing Institute of Technology, Beijing 100081, China
- Material Science Center, Yangtze Delta Region Academy of Beijing Institute of Technology, Jiaxing, China
| | - Cong Xiao
- Institute of Applied Physics and Materials Engineering, University of Macau, Taipa, Macau, China
- Department of Physics, The University of Hong Kong, Hong Kong, China
- HKU-UCAS Joint Institute of Theoretical and Computational Physics at Hong Kong, China
| | - Shengyuan A Yang
- Institute of Applied Physics and Materials Engineering, University of Macau, Taipa, Macau, China
| | - Xiaosong Wu
- State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, Frontiers Science Center for Nano-optoelectronics, Peking University, Beijing 100871, China
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
- Peking University Yangtze Delta Institute of Optoelectronics, Nantong 226010, Jiangsu, China
| |
Collapse
|
2
|
Lodge MS, Marcellina E, Zhu Z, Li XP, Kaczorowski D, Fuhrer MS, Yang SA, Weber B. Symmetry-selective quasiparticle scattering and electric field tunability of the ZrSiS surface electronic structure. Nanotechnology 2024; 35:195704. [PMID: 38316053 DOI: 10.1088/1361-6528/ad2639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Accepted: 02/05/2024] [Indexed: 02/07/2024]
Abstract
Three-dimensional Dirac semimetals with square-net non-symmorphic symmetry, such as ternary ZrXY (X = Si, Ge; Y = S, Se, Te) compounds, have attracted significant attention owing to the presence of topological nodal lines, loops, or networks in their bulk. Orbital symmetry plays a profound role in such materials as the different branches of the nodal dispersion can be distinguished by their distinct orbital symmetry eigenvalues. The presence of different eigenvalues suggests that scattering between states of different orbital symmetry may be strongly suppressed. Indeed, in ZrSiS, there has been no clear experimental evidence of quasiparticle scattering reported between states of different symmetry eigenvalues at small wave vectorq⃗.Here we show, using quasiparticle interference, that atomic step-edges in the ZrSiS surface facilitate quasiparticle scattering between states of different symmetry eigenvalues. This symmetry eigenvalue mixing quasiparticle scattering is the first to be reported for ZrSiS and contrasts quasiparticle scattering with no mixing of symmetry eigenvalues, where the latter occurs with scatterers preserving the glide mirror symmetry of the crystal lattice, e.g. native point defects in ZrSiS. Finally, we show that the electronic structure of the ZrSiS surface, including its unique floating band surface state, can be tuned by a vertical electric field locally applied by the tip of a scanning tunneling microscope (STM), enabling control of a spin-orbit induced avoided crossing near the Fermi level by as much as 300%.
Collapse
Affiliation(s)
- Michael S Lodge
- School of Physical and Mathematical Sciences, Nanyang Technological University, 637371, Singapore
- Department of Physics, University of Central Florida, Orlando, FL 32816, United States of America
- NanoScience Technology Center, University of Central Florida, Orlando, FL 32826, United States of America
| | - Elizabeth Marcellina
- School of Physical and Mathematical Sciences, Nanyang Technological University, 637371, Singapore
| | - Ziming Zhu
- Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education, Department of Physics and Synergetic Innovation Center for Quantum Effects and Applications, Hunan Normal University, Changsha 410081, People's Republic of China
| | - Xiao-Ping Li
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, 487372, Singapore
| | - Dariusz Kaczorowski
- Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Okólna 2, 50-422 Wrocław, Poland
| | - Michael S Fuhrer
- School of Physics and Astronomy, Monash University, Clayton VIC 3800 Australia Monash Centre for Atomically Thin Materials, Monash University, Clayton VIC 3800, Australia
- Australian Research Council (ARC) Centre of Excellence for Low-Energy Electronics Technologies (FLEET), School of Physics, Monash University, Clayton VIC 3800, Australia
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, 487372, Singapore
| | - Bent Weber
- School of Physical and Mathematical Sciences, Nanyang Technological University, 637371, Singapore
- Australian Research Council (ARC) Centre of Excellence for Low-Energy Electronics Technologies (FLEET), School of Physics, Monash University, Clayton VIC 3800, Australia
| |
Collapse
|
3
|
Dai Y, Xiong J, Ge Y, Cheng B, Wang L, Wang P, Liu Z, Yan S, Zhang C, Xu X, Shi Y, Cheong SW, Xiao C, Yang SA, Liang SJ, Miao F. Interfacial magnetic spin Hall effect in van der Waals Fe 3GeTe 2/MoTe 2 heterostructure. Nat Commun 2024; 15:1129. [PMID: 38321042 PMCID: PMC10847462 DOI: 10.1038/s41467-024-45318-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 01/19/2024] [Indexed: 02/08/2024] Open
Abstract
The spin Hall effect (SHE) allows efficient generation of spin polarization or spin current through charge current and plays a crucial role in the development of spintronics. While SHE typically occurs in non-magnetic materials and is time-reversal even, exploring time-reversal-odd (T-odd) SHE, which couples SHE to magnetization in ferromagnetic materials, offers a new charge-spin conversion mechanism with new functionalities. Here, we report the observation of giant T-odd SHE in Fe3GeTe2/MoTe2 van der Waals heterostructure, representing a previously unidentified interfacial magnetic spin Hall effect (interfacial-MSHE). Through rigorous symmetry analysis and theoretical calculations, we attribute the interfacial-MSHE to a symmetry-breaking induced spin current dipole at the vdW interface. Furthermore, we show that this linear effect can be used for implementing multiply-accumulate operations and binary convolutional neural networks with cascaded multi-terminal devices. Our findings uncover an interfacial T-odd charge-spin conversion mechanism with promising potential for energy-efficient in-memory computing.
Collapse
Affiliation(s)
- Yudi Dai
- National Laboratory of Solid State Microstructures, Institute of Brain-Inspired Intelligence, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Junlin Xiong
- National Laboratory of Solid State Microstructures, Institute of Brain-Inspired Intelligence, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Yanfeng Ge
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore, Singapore
| | - Bin Cheng
- Institute of Interdisciplinary Physical Sciences, School of Science, Nanjing University of Science and Technology, Nanjing, 210094, China.
| | - Lizheng Wang
- National Laboratory of Solid State Microstructures, Institute of Brain-Inspired Intelligence, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Pengfei Wang
- National Laboratory of Solid State Microstructures, Institute of Brain-Inspired Intelligence, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Zenglin Liu
- National Laboratory of Solid State Microstructures, Institute of Brain-Inspired Intelligence, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Shengnan Yan
- National Laboratory of Solid State Microstructures, Institute of Brain-Inspired Intelligence, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Cuiwei Zhang
- Institute of Physics, Chinese Academy of Sciences, 100190, Beijing, China
| | - Xianghan Xu
- Center for Quantum Materials Synthesis and Department of Physics and Astronomy, Rutgers, The State University of New Jersey, Piscataway, NJ, 08854, USA
| | - Youguo Shi
- Institute of Physics, Chinese Academy of Sciences, 100190, Beijing, China
| | - Sang-Wook Cheong
- Center for Quantum Materials Synthesis and Department of Physics and Astronomy, Rutgers, The State University of New Jersey, Piscataway, NJ, 08854, USA
| | - Cong Xiao
- Institute of Applied Physics and Materials Engineering, University of Macau, Taipa, Macau, SAR, China.
- Department of Physics, University of Hong Kong, Hong Kong, China.
- HKU-UCAS Joint Institute of Theoretical and Computational Physics at Hong Kong, Hong Kong, China.
| | - Shengyuan A Yang
- Institute of Applied Physics and Materials Engineering, University of Macau, Taipa, Macau, SAR, China
| | - Shi-Jun Liang
- National Laboratory of Solid State Microstructures, Institute of Brain-Inspired Intelligence, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China.
| | - Feng Miao
- National Laboratory of Solid State Microstructures, Institute of Brain-Inspired Intelligence, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China.
| |
Collapse
|
4
|
Zhao D, Gao R, Cheng W, Wen M, Zhang X, Yokota T, Sellin P, Yang SA, Shang L, Zhou C, Someya T, Jie W, Xu Y. Heavy-to-light electron transition enabling real-time spectra detection of charged particles by a biocompatible semiconductor. Nat Commun 2024; 15:1115. [PMID: 38321015 PMCID: PMC10847108 DOI: 10.1038/s41467-024-45089-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 01/15/2024] [Indexed: 02/08/2024] Open
Abstract
The current challenge of wearable/implantable personal dosimeters for medical diagnosis and radiotherapy applications is lack of suitable detector materials possessing both excellent detection performance and biocompatibility. Here, we report a solution-grown biocompatible organic single crystalline semiconductor (OSCS), 4-Hydroxyphenylacetic acid (4HPA), achieving real-time spectral detection of charged particles with single-particle sensitivity. Along in-plane direction, two-dimensional anisotropic 4HPA exhibits a large electron drift velocity of 5 × 105 cm s-1 at "radiation-mode" while maintaining a high resistivity of (1.28 ± 0.003) × 1012 Ω·cm at "dark-mode" due to influence of dense π-π overlaps and high-energy L1 level. Therefore, 4HPA detectors exhibit the record spectra detection of charged particles among their organic counterparts, with energy resolution of 36%, (μt)e of (4.91 ± 0.07) × 10-5 cm2 V-1, and detection time down to 3 ms. These detectors also show high X-ray detection sensitivity of 16,612 μC Gyabs-1 cm-3, detection of limit of 20 nGyair s-1, and long-term stability after 690 Gyair irradiation.
Collapse
Affiliation(s)
- Dou Zhao
- State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, 710072, Xi'an, Shaanxi, China
- Department of Electrical Engineering and Information Systems, The University of Tokyo, Tokyo, 113-8656, Japan
| | - Ruiling Gao
- International Center of Quantum and Molecular Structures, Shanghai University, 200444, Shanghai, China
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore, 487372, Singapore
| | - Wei Cheng
- Department of Nuclear Science and Engineering, Nanjing University of Aeronautics and Astronautics, 211106, Nanjing, China
| | - Mengyao Wen
- State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, 710072, Xi'an, Shaanxi, China
| | - Xinlei Zhang
- School of Physics and Information Technology, Shaanxi Normal University, 710119, Xi'an, Shaanxi, China
| | - Tomoyuki Yokota
- Department of Electrical Engineering and Information Systems, The University of Tokyo, Tokyo, 113-8656, Japan
| | - Paul Sellin
- Department of Physics, University of Surrey, Guildford, GU2 7XH, UK
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore, 487372, Singapore
| | - Li Shang
- State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, 710072, Xi'an, Shaanxi, China
| | - Chongjian Zhou
- State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, 710072, Xi'an, Shaanxi, China
| | - Takao Someya
- Department of Electrical Engineering and Information Systems, The University of Tokyo, Tokyo, 113-8656, Japan.
| | - Wanqi Jie
- State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, 710072, Xi'an, Shaanxi, China.
| | - Yadong Xu
- State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, 710072, Xi'an, Shaanxi, China.
| |
Collapse
|
5
|
Wang H, Huang YX, Liu H, Feng X, Zhu J, Wu W, Xiao C, Yang SA. Orbital Origin of the Intrinsic Planar Hall Effect. Phys Rev Lett 2024; 132:056301. [PMID: 38364160 DOI: 10.1103/physrevlett.132.056301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 10/12/2023] [Accepted: 12/20/2023] [Indexed: 02/18/2024]
Abstract
Recent experiments reported an antisymmetric planar Hall effect, where the Hall current is odd in the in plane magnetic field and scales linearly with both electric and magnetic fields applied. Existing theories rely exclusively on a spin origin, which requires spin-orbit coupling to take effect. Here, we develop a general theory for the intrinsic planar Hall effect (IPHE), highlighting a previously unknown orbital mechanism and connecting it to a band geometric quantity-the anomalous orbital polarizability (AOP). Importantly, the orbital mechanism does not request spin-orbit coupling, so sizable IPHE can occur and is dominated by an orbital contribution in systems with weak spin-orbit coupling. Combined with first-principles calculations, we demonstrate our theory with quantitative evaluation for bulk materials TaSb_{2}, NbAs_{2}, and SrAs_{3}. We further show that AOP and its associated orbital IPHE can be greatly enhanced at topological band crossings, offering a new way to probe topological materials.
Collapse
Affiliation(s)
- Hui Wang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Yue-Xin Huang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
- School of Sciences, Great Bay University, Dongguan 523000, China
- Great Bay Institute for Advanced Study, Dongguan 523000, China
| | - Huiying Liu
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
- School of Physics, Beihang University, Beijing 100191, China
| | - Xiaolong Feng
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, D-01187 Dresden, Germany
| | - Jiaojiao Zhu
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Weikang Wu
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
- Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan 250061, China
| | - Cong Xiao
- Institute of Applied Physics and Materials Engineering, University of Macau, Macau, China
- Department of Physics, The University of Hong Kong, Hong Kong, China
- HKU-UCAS Joint Institute of Theoretical and Computational Physics at Hong Kong, Hong Kong, China
| | - Shengyuan A Yang
- Institute of Applied Physics and Materials Engineering, University of Macau, Macau, China
| |
Collapse
|
6
|
Zheng B, Feng X, Liu B, Liu Z, Wang S, Zhang Y, Ma X, Luo Y, Wang C, Li R, Zhang Z, Cui S, Lu Y, Sun Z, He J, Yang SA, Xiang B. The Coexistence of Superconductivity and Topological Order in Van der Waals InNbS 2. Small 2024; 20:e2305909. [PMID: 37759426 DOI: 10.1002/smll.202305909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Revised: 09/06/2023] [Indexed: 09/29/2023]
Abstract
The research on systems with coexistence of superconductivity and nontrivial band topology has attracted widespread attention. However, the limited availability of material platforms severely hinders the research progress. Here, it reports the first experimental synthesis and measurement of high-quality single crystal van der Waals transition-metal dichalcogenide InNbS2 , revealing it as a topological nodal line semimetal with coexisting superconductivity. The temperature-dependent measurements of magnetization susceptibility and electrical transport show that InNbS2 is a type-II superconductor with a transition temperature Tc of 6 K. First-principles calculations predict multiple topological nodal ring states close to the Fermi level in the presence of spin-orbit coupling. Similar features are also observed in the as-synthesized BiNbS2 and PbNbS2 samples. This work provides new material platforms ANbS2 (A = In, Bi, and Pb) and uncovers their intriguing potential for exploring the interplay between superconductivity and band topology.
Collapse
Affiliation(s)
- Bo Zheng
- Department of Materials Science & Engineering, CAS Key Lab of Materials for Energy Conversion, Anhui Laboratory of Advanced Photon Science and Technology, University of Science and Technology of China, Hefei, 230026, China
| | - Xukun Feng
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore, 487372, Singapore
| | - Bo Liu
- Department of Physics and CAS Key Laboratory of Strongly-coupled Quantum Matter Physics, University of Science and Technology of China, Hefei, Anhui, 230026, China
| | - Zhanfeng Liu
- National Synchrotron Radiation Laboratory, CAS Center for Excellence in Nanoscience, University of Science and Technology of China, Hefei, Anhui, 230029, China
| | - Shasha Wang
- Department of Materials Science & Engineering, CAS Key Lab of Materials for Energy Conversion, Anhui Laboratory of Advanced Photon Science and Technology, University of Science and Technology of China, Hefei, 230026, China
| | - Ying Zhang
- Department of Materials Science & Engineering, CAS Key Lab of Materials for Energy Conversion, Anhui Laboratory of Advanced Photon Science and Technology, University of Science and Technology of China, Hefei, 230026, China
| | - Xiang Ma
- Department of Materials Science & Engineering, CAS Key Lab of Materials for Energy Conversion, Anhui Laboratory of Advanced Photon Science and Technology, University of Science and Technology of China, Hefei, 230026, China
| | - Yang Luo
- Department of Physics and CAS Key Laboratory of Strongly-coupled Quantum Matter Physics, University of Science and Technology of China, Hefei, Anhui, 230026, China
| | - Changlong Wang
- Department of Materials Science & Engineering, CAS Key Lab of Materials for Energy Conversion, Anhui Laboratory of Advanced Photon Science and Technology, University of Science and Technology of China, Hefei, 230026, China
| | - Ruimin Li
- Department of Materials Science & Engineering, CAS Key Lab of Materials for Energy Conversion, Anhui Laboratory of Advanced Photon Science and Technology, University of Science and Technology of China, Hefei, 230026, China
| | - Zeying Zhang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore, 487372, Singapore
- College of Mathematics and Physics, Beijing University of Chemical Technology, Beijing, 100029, China
| | - Shengtao Cui
- National Synchrotron Radiation Laboratory, CAS Center for Excellence in Nanoscience, University of Science and Technology of China, Hefei, Anhui, 230029, China
| | - Yalin Lu
- Department of Materials Science & Engineering, CAS Key Lab of Materials for Energy Conversion, Anhui Laboratory of Advanced Photon Science and Technology, University of Science and Technology of China, Hefei, 230026, China
| | - Zhe Sun
- National Synchrotron Radiation Laboratory, CAS Center for Excellence in Nanoscience, University of Science and Technology of China, Hefei, Anhui, 230029, China
| | - Junfeng He
- Department of Physics and CAS Key Laboratory of Strongly-coupled Quantum Matter Physics, University of Science and Technology of China, Hefei, Anhui, 230026, China
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore, 487372, Singapore
| | - Bin Xiang
- Department of Materials Science & Engineering, CAS Key Lab of Materials for Energy Conversion, Anhui Laboratory of Advanced Photon Science and Technology, University of Science and Technology of China, Hefei, 230026, China
| |
Collapse
|
7
|
Zhong S, Zhang X, Liu S, Yang SA, Lu Y. Giant and Nonanalytic Negative Piezoelectric Response in Elemental Group-Va Ferroelectric Monolayers. Phys Rev Lett 2023; 131:236801. [PMID: 38134770 DOI: 10.1103/physrevlett.131.236801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Accepted: 10/24/2023] [Indexed: 12/24/2023]
Abstract
Materials with negative longitudinal piezoelectric response have been a focus of recent research. So far, reported examples are mostly three-dimensional bulk materials, either compounds with strong ionic bonds or layered materials with van der Waals interlayer gaps. Here, we report the first example in two-dimensional elemental materials-the class of group-Va monolayers. From first-principles calculations, we show that these materials possess giant negative longitudinal piezoelectric coefficient e_{11}. Importantly, its physical mechanism is also distinct from all previous proposals, connected with the special buckling driven polarization in these elemental systems. As a result, the usually positive internal strain contribution to piezoelectricity becomes negative and even dominates over the clamped ion contribution in Bi monolayers. Based on this new mechanism, we also find several 2D crystal structures that may support negative longitudinal piezoelectricity. As another consequence, piezoelectric response in Bi monolayers exhibits a significant nonanalytic behavior, namely, the e_{11} coefficient takes sizably different values (differed by ∼18%) under tensile and compressive strains, a phenomenon not known before and helpful for the development of novel electromechanical devices.
Collapse
Affiliation(s)
- Shulin Zhong
- School of Physics, Zhejiang University, Hangzhou 310027, Zhejiang Province, China
| | - Xuanlin Zhang
- State Key Laboratory of Silicon and Advanced Semiconductor Materials, School of Materials Science & Engineering, Zhejiang University, Hangzhou 310027, Zhejiang Province, China
| | - Shi Liu
- Key Laboratory for Quantum Materials of Zhejiang Province, Department of Physics, School of Science, Westlake University, 600 Dunyu Road, Hangzhou 310030, Zhejiang Province, China
- Institute of Natural Sciences, Westlake Institute for Advanced Study, 18 Shilongshan Road, Hangzhou 310024, Zhejiang Province, China
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, IAPME, Faculty of Science and Technology, University of Macau, Macau SAR, China
| | - Yunhao Lu
- School of Physics, Zhejiang University, Hangzhou 310027, Zhejiang Province, China
- State Key Laboratory of Silicon and Advanced Semiconductor Materials, School of Materials Science & Engineering, Zhejiang University, Hangzhou 310027, Zhejiang Province, China
| |
Collapse
|
8
|
Zhang X, He T, Liu Y, Dai X, Liu G, Chen C, Wu W, Zhu J, Yang SA. Magnetic Real Chern Insulator in 2D Metal-Organic Frameworks. Nano Lett 2023; 23:7358-7363. [PMID: 37535707 DOI: 10.1021/acs.nanolett.3c01723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/05/2023]
Abstract
Real Chern insulators have attracted great interest, but so far, their material realization is limited to nonmagnetic crystals and systems without spin-orbit coupling. Here, we reveal the magnetic real Chern insulator (MRCI) state in a recently synthesized metal-organic framework material Co3(HITP)2. Its ground state with in-plane ferromagnetic ordering hosts a nontrivial real Chern number, enabled by the C2zT symmetry and robustness against spin-orbit coupling. Distinct from previous nonmagnetic examples, the topological corner zero modes of MRCIs are spin-polarized. Furthermore, under small tensile strains, the material undergoes a topological phase transition from the MRCI to a magnetic double-Weyl semimetal phase, via a pseudospin-1 critical state. Similar physics can also be found in closely related materials Mn3(HITP)2 and Fe3(HITP)2, which also exist. Possible experimental detections and implications of an emerging magnetic flat band in the system are discussed.
Collapse
Affiliation(s)
- Xiaoming Zhang
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Hebei University of Technology, Tianjin 300130, China
- School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China
| | - Tingli He
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Hebei University of Technology, Tianjin 300130, China
- School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China
| | - Ying Liu
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Hebei University of Technology, Tianjin 300130, China
- School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China
| | - Xuefang Dai
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Hebei University of Technology, Tianjin 300130, China
- School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China
| | - Guodong Liu
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Hebei University of Technology, Tianjin 300130, China
- School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China
| | - Cong Chen
- Department of Physics, The University of Hong Kong, Hong Kong, China
- HKU-UCAS Joint Institute of Theoretical and Computational Physics at Hong Kong, Hong Kong, China
| | - Weikang Wu
- Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education), Shandong University, Jinan 250061, China
| | - Jiaojiao Zhu
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| |
Collapse
|
9
|
Gou J, Bai H, Zhang X, Huang YL, Duan S, Ariando A, Yang SA, Chen L, Lu Y, Wee ATS. Two-dimensional ferroelectricity in a single-element bismuth monolayer. Nature 2023; 617:67-72. [PMID: 37020017 PMCID: PMC10156600 DOI: 10.1038/s41586-023-05848-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 02/15/2023] [Indexed: 04/07/2023]
Abstract
Ferroelectric materials are fascinating for their non-volatile switchable electric polarizations induced by the spontaneous inversion-symmetry breaking. However, in all of the conventional ferroelectric compounds, at least two constituent ions are required to support the polarization switching1,2. Here, we report the observation of a single-element ferroelectric state in a black phosphorus-like bismuth layer3, in which the ordered charge transfer and the regular atom distortion between sublattices happen simultaneously. Instead of a homogenous orbital configuration that ordinarily occurs in elementary substances, we found the Bi atoms in a black phosphorous-like Bi monolayer maintain a weak and anisotropic sp orbital hybridization, giving rise to the inversion-symmetry-broken buckled structure accompanied with charge redistribution in the unit cell. As a result, the in-plane electric polarization emerges in the Bi monolayer. Using the in-plane electric field produced by scanning probe microscopy, ferroelectric switching is further visualized experimentally. Owing to the conjugative locking between the charge transfer and atom displacement, we also observe the anomalous electric potential profile at the 180° tail-to-tail domain wall induced by competition between the electronic structure and electric polarization. This emergent single-element ferroelectricity broadens the mechanism of ferroelectrics and may enrich the applications of ferroelectronics in the future.
Collapse
Affiliation(s)
- Jian Gou
- Department of Physics, National University of Singapore, Singapore, Singapore.
| | - Hua Bai
- Zhejiang Province Key Laboratory of Quantum Technology and Device, School of Physics, State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, China
- Department of Physics, Faculty of Science, Kunming University of Science and Technology, Kunming, China
| | - Xuanlin Zhang
- Zhejiang Province Key Laboratory of Quantum Technology and Device, School of Physics, State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, China
| | - Yu Li Huang
- Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University, Fuzhou, China
| | - Sisheng Duan
- Department of Physics, National University of Singapore, Singapore, Singapore
| | - A Ariando
- Department of Physics, National University of Singapore, Singapore, Singapore
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore, Singapore
| | - Lan Chen
- Institute of Physics, Chinese Academy of Sciences, Beijing, China.
- School of Physics, University of Chinese Academy of Sciences, Beijing, China.
| | - Yunhao Lu
- Zhejiang Province Key Laboratory of Quantum Technology and Device, School of Physics, State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, China.
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore, Singapore, Singapore.
- Centre for Advanced 2D Materials (CA2DM) and Graphene Research Centre (GRC), National University of Singapore, Singapore, Singapore.
| |
Collapse
|
10
|
Xiao C, Wu W, Wang H, Huang YX, Feng X, Liu H, Guo GY, Niu Q, Yang SA. Time-Reversal-Even Nonlinear Current Induced Spin Polarization. Phys Rev Lett 2023; 130:166302. [PMID: 37154629 DOI: 10.1103/physrevlett.130.166302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Accepted: 03/23/2023] [Indexed: 05/10/2023]
Abstract
We propose a time-reversal-even spin generation in second order of electric fields, which dominates the current induced spin polarization in a wide class of centrosymmetric nonmagnetic materials, and leads to a novel nonlinear spin-orbit torque in magnets. We reveal a quantum origin of this effect from the momentum space dipole of the anomalous spin polarizability. First-principles calculations predict sizable spin generations in several nonmagnetic hcp metals, in monolayer TiTe_{2}, and in ferromagnetic monolayer MnSe_{2}, which can be detected in experiment. Our work opens up the broad vista of nonlinear spintronics in both nonmagnetic and magnetic systems.
Collapse
Affiliation(s)
- Cong Xiao
- Department of Physics, The University of Hong Kong, Hong Kong, People's Republic of China
- HKU-UCAS Joint Institute of Theoretical and Computational Physics at Hong Kong, Hong Kong, China
| | - Weikang Wu
- Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan 250061, People's Republic of China
| | - Hui Wang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Yue-Xin Huang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Xiaolong Feng
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Huiying Liu
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
- School of Physics, Beihang University, Beijing 100191, China
| | - Guang-Yu Guo
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan, Republic of China
- Physics Division, National Center for Theoretical Sciences, Taipei 10617, Taiwan, Republic of China
| | - Qian Niu
- School of Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| |
Collapse
|
11
|
Huang YX, Feng X, Wang H, Xiao C, Yang SA. Intrinsic Nonlinear Planar Hall Effect. Phys Rev Lett 2023; 130:126303. [PMID: 37027844 DOI: 10.1103/physrevlett.130.126303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2022] [Accepted: 02/23/2023] [Indexed: 06/19/2023]
Abstract
We propose an intrinsic nonlinear planar Hall effect, which is of band geometric origin, independent of scattering, and scales with the second order of electric field and first order of magnetic field. We show that this effect is less symmetry constrained compared with other nonlinear transport effects and is supported in a large class of nonmagnetic polar and chiral crystals. Its characteristic angular dependence provides an effective way to control the nonlinear output. Combined with first-principles calculations, we evaluate this effect in the Janus monolayer MoSSe and report experimentally measurable results. Our work reveals an intrinsic transport effect, which offers a new tool for material characterization and a new mechanism for nonlinear device application.
Collapse
Affiliation(s)
- Yue-Xin Huang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Xiaolong Feng
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Hui Wang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Cong Xiao
- Department of Physics, The University of Hong Kong, Hong Kong, China
- HKU-UCAS Joint Institute of Theoretical and Computational Physics at Hong Kong, Hong Kong, China
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| |
Collapse
|
12
|
Kong L, Sun C, You M, Jiang Y, Wang G, Wang L, Zhang C, Chen S, Wang S, Yang SA, Wang S, Yang Y, Zhang X, Yuan M, Yang X. Universal Molecular Control Strategy for Scalable Fabrication of Perovskite Light-Emitting Diodes. Nano Lett 2023; 23:985-992. [PMID: 36715576 DOI: 10.1021/acs.nanolett.2c04459] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Despite the rapid progress in perovskite light-emitting diodes (PeLEDs), the electroluminescence performance of large-area perovskite devices lags far behind that of laboratory-size ones. Here, we report a 3.5 cm × 3.5 cm large-area PeLED with a record-high external quantum efficiency of 12.1% by creating an amphipathic molecular interface modifier of betaine citrate (BC) between the perovskite layer and the underlying hole transport layer (HTL). It is found that the surface wettability for various HTLs can be efficiently improved as a result of the coexistence of methyl and carboxyl groups in the BC molecules that makes favorable groups to selectively contact with the HTL surface and increases the surface free energy, which greatly facilitates the scalable process of solution-processed perovskite films. Moreover, the luminous performance of perovskite emitters is simultaneously enhanced through the coordination between C═O in the carboxyl groups and Pb dangling bonds.
Collapse
Affiliation(s)
- Lingmei Kong
- Key Laboratory of Advanced Display and System Applications of Ministry of Education, Shanghai University, Shanghai200072, P. R. China
| | - Changjiu Sun
- Key Laboratory of Advanced Energy Materials Chemistry of Ministry of Education, Renewable Energy Conversion and Storage Center (RECAST), College of Chemistry, Nankai University, Tianjin300071, P. R. China
| | - Mengqing You
- Key Laboratory of Advanced Display and System Applications of Ministry of Education, Shanghai University, Shanghai200072, P. R. China
| | - Yuanzhi Jiang
- Key Laboratory of Advanced Energy Materials Chemistry of Ministry of Education, Renewable Energy Conversion and Storage Center (RECAST), College of Chemistry, Nankai University, Tianjin300071, P. R. China
| | - Guangzhao Wang
- Key Laboratory of Extraordinary Bond Engineering and Advanced Materials Technology of Chongqing, School of Electronic Information Engineering, Yangtze Normal University, Chongqing408100, P. R. China
| | - Lin Wang
- Key Laboratory of Advanced Display and System Applications of Ministry of Education, Shanghai University, Shanghai200072, P. R. China
| | - Chengxi Zhang
- Key Laboratory of Advanced Display and System Applications of Ministry of Education, Shanghai University, Shanghai200072, P. R. China
| | - Shi Chen
- Materials Genome Institute, Shanghai University, Shanghai200444, P. R. China
| | - Sheng Wang
- Key Laboratory of Advanced Display and System Applications of Ministry of Education, Shanghai University, Shanghai200072, P. R. China
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore487372, Singapore
| | - Shenghao Wang
- Materials Genome Institute, Shanghai University, Shanghai200444, P. R. China
| | - Yingguo Yang
- Shanghai Synchrotron Radiation Facility (SSRF), Zhangjiang Lab, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai201204, P. R. China
| | - Xiaoyu Zhang
- College of Materials Science and Engineering, Jilin University, Changchun130012, P. R. China
| | - Mingjian Yuan
- Key Laboratory of Advanced Energy Materials Chemistry of Ministry of Education, Renewable Energy Conversion and Storage Center (RECAST), College of Chemistry, Nankai University, Tianjin300071, P. R. China
| | - Xuyong Yang
- Key Laboratory of Advanced Display and System Applications of Ministry of Education, Shanghai University, Shanghai200072, P. R. China
| |
Collapse
|
13
|
Guo SD, Feng XK, Zhu YT, Wang G, Yang SA. Two-dimensional Janus Si dichalcogenides: a first-principles study. Phys Chem Chem Phys 2023; 25:2274-2281. [PMID: 36597784 DOI: 10.1039/d2cp04536b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Strong structural asymmetry is actively explored in two-dimensional (2D) materials, because it can give rise to many interesting physical properties. Motivated by the recent synthesis of monolayer Si2Te2, we explored a family of 2D materials, named Janus Si dichalcogenides (JSD), which parallel the Janus transition metal dichalcogenides and exhibit even stronger inversion asymmetry. Using first-principles calculations, we show that their strong structural asymmetry leads to a pronounced intrinsic polar field, sizable spin splitting, and large piezoelectric response. The spin splitting involves an out-of-plane spin component, which is beyond the linear Rashba model. The piezoelectric tensor has a large value in both in-plane d11 coefficient and out-of-plane d31 coefficient, making monolayer JSDs distinct among existing 2D piezoelectric materials. In addition, we find interesting strain-induced phase transitions in these materials. Particularly, there are multiple valleys that compete for the conduction band minimum, which will lead to notable changes in the optical and transport properties under strain. Our work reveals a new family of Si based 2D materials, which could find promising applications in spintronic and piezoelectric devices.
Collapse
Affiliation(s)
- San-Dong Guo
- School of Electronic Engineering, Xi'an University of Posts and Telecommunications, Xi'an 710121, China.
| | - Xu-Kun Feng
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Yu-Tong Zhu
- School of Electronic Engineering, Xi'an University of Posts and Telecommunications, Xi'an 710121, China.
| | - Guangzhao Wang
- Key Laboratory of Extraordinary Bond Engineering and Advanced Materials Technology of Chongqing, School of Electronic Information Engineering, Yangtze Normal University, Chongqing 408100, China
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| |
Collapse
|
14
|
Ye XG, Liu H, Zhu PF, Xu WZ, Yang SA, Shang N, Liu K, Liao ZM. Control over Berry Curvature Dipole with Electric Field in WTe_{2}. Phys Rev Lett 2023; 130:016301. [PMID: 36669212 DOI: 10.1103/physrevlett.130.016301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 09/28/2022] [Accepted: 12/18/2022] [Indexed: 06/17/2023]
Abstract
Berry curvature dipole plays an important role in various nonlinear quantum phenomena. However, the maximum symmetry allowed for nonzero Berry curvature dipole in the transport plane is a single mirror line, which strongly limits its effects in materials. Here, via probing the nonlinear Hall effect, we demonstrate the generation of Berry curvature dipole by applied dc electric field in WTe_{2}, which is used to break the symmetry constraint. A linear dependence between the dipole moment of Berry curvature and the dc electric field is observed. The polarization direction of the Berry curvature is controlled by the relative orientation of the electric field and crystal axis, which can be further reversed by changing the polarity of the dc field. Our Letter provides a route to generate and control Berry curvature dipole in broad material systems and to facilitate the development of nonlinear quantum devices.
Collapse
Affiliation(s)
- Xing-Guo Ye
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Huiying Liu
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore, 487372, Singapore
| | - Peng-Fei Zhu
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Wen-Zheng Xu
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore, 487372, Singapore
| | - Nianze Shang
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Kaihui Liu
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Zhi-Min Liao
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| |
Collapse
|
15
|
Chen Q, Chen F, Pan Y, Cui C, Yan Q, Zhang L, Gao Z, Yang SA, Yu ZM, Chen H, Zhang B, Yang Y. Discovery of a maximally charged Weyl point. Nat Commun 2022; 13:7359. [PMID: 36450711 PMCID: PMC9712526 DOI: 10.1038/s41467-022-34978-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 11/14/2022] [Indexed: 12/03/2022] Open
Abstract
The hypothetical Weyl particles in high-energy physics have been discovered in three-dimensional crystals as collective quasiparticle excitations near two-fold degenerate Weyl points. Such momentum-space Weyl particles carry quantised chiral charges, which can be measured by counting the number of Fermi arcs emanating from the corresponding Weyl points. It is known that merging unit-charged Weyl particles can create new ones with more charges. However, only very recently has it been realised that there is an upper limit - the maximal charge number that a two-fold Weyl point can host is four - achievable only in crystals without spin-orbit coupling. Here, we report the experimental realisation of such a maximally charged Weyl point in a three-dimensional photonic crystal. The four charges support quadruple-helicoid Fermi arcs, forming an unprecedented topology of two non-contractible loops in the surface Brillouin zone. The helicoid Fermi arcs also exhibit the long-pursued type-II van Hove singularities that can reside at arbitrary momenta. This discovery reveals a type of maximally charged Weyl particles beyond conventional topological particles in crystals.
Collapse
Affiliation(s)
- Qiaolu Chen
- grid.13402.340000 0004 1759 700XInterdisciplinary Centre for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Centre, Zhejiang University, Hangzhou, 310027 China ,grid.13402.340000 0004 1759 700XInternational Joint Innovation Centre, Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang, The Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining, 314400 China ,grid.13402.340000 0004 1759 700XJinhua Institute of Zhejiang University, Zhejiang University, Jinhua, 321099 China
| | - Fujia Chen
- grid.13402.340000 0004 1759 700XInterdisciplinary Centre for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Centre, Zhejiang University, Hangzhou, 310027 China ,grid.13402.340000 0004 1759 700XInternational Joint Innovation Centre, Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang, The Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining, 314400 China ,grid.13402.340000 0004 1759 700XJinhua Institute of Zhejiang University, Zhejiang University, Jinhua, 321099 China
| | - Yuang Pan
- grid.13402.340000 0004 1759 700XInterdisciplinary Centre for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Centre, Zhejiang University, Hangzhou, 310027 China ,grid.13402.340000 0004 1759 700XInternational Joint Innovation Centre, Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang, The Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining, 314400 China ,grid.13402.340000 0004 1759 700XJinhua Institute of Zhejiang University, Zhejiang University, Jinhua, 321099 China
| | - Chaoxi Cui
- grid.43555.320000 0000 8841 6246Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing, 100081 China ,grid.43555.320000 0000 8841 6246Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems, School of Physics, Beijing Institute of Technology, Beijing, 100081 China
| | - Qinghui Yan
- grid.13402.340000 0004 1759 700XInterdisciplinary Centre for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Centre, Zhejiang University, Hangzhou, 310027 China ,grid.13402.340000 0004 1759 700XInternational Joint Innovation Centre, Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang, The Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining, 314400 China ,grid.13402.340000 0004 1759 700XJinhua Institute of Zhejiang University, Zhejiang University, Jinhua, 321099 China
| | - Li Zhang
- grid.13402.340000 0004 1759 700XInterdisciplinary Centre for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Centre, Zhejiang University, Hangzhou, 310027 China ,grid.13402.340000 0004 1759 700XInternational Joint Innovation Centre, Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang, The Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining, 314400 China ,grid.13402.340000 0004 1759 700XJinhua Institute of Zhejiang University, Zhejiang University, Jinhua, 321099 China
| | - Zhen Gao
- grid.263817.90000 0004 1773 1790Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, 518055 China
| | - Shengyuan A. Yang
- grid.263662.50000 0004 0500 7631Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore, 487372 Singapore
| | - Zhi-Ming Yu
- grid.43555.320000 0000 8841 6246Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing, 100081 China ,grid.43555.320000 0000 8841 6246Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems, School of Physics, Beijing Institute of Technology, Beijing, 100081 China
| | - Hongsheng Chen
- grid.13402.340000 0004 1759 700XInterdisciplinary Centre for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Centre, Zhejiang University, Hangzhou, 310027 China ,grid.13402.340000 0004 1759 700XInternational Joint Innovation Centre, Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang, The Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining, 314400 China ,grid.13402.340000 0004 1759 700XJinhua Institute of Zhejiang University, Zhejiang University, Jinhua, 321099 China
| | - Baile Zhang
- grid.59025.3b0000 0001 2224 0361Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 637371 Singapore ,grid.59025.3b0000 0001 2224 0361Centre for Disruptive Photonic Technologies, The Photonics Institute, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798 Singapore
| | - Yihao Yang
- grid.13402.340000 0004 1759 700XInterdisciplinary Centre for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Centre, Zhejiang University, Hangzhou, 310027 China ,grid.13402.340000 0004 1759 700XInternational Joint Innovation Centre, Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang, The Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining, 314400 China ,grid.13402.340000 0004 1759 700XJinhua Institute of Zhejiang University, Zhejiang University, Jinhua, 321099 China
| |
Collapse
|
16
|
Liu GG, Gao Z, Wang Q, Xi X, Hu YH, Wang M, Liu C, Lin X, Deng L, Yang SA, Zhou P, Yang Y, Chong Y, Zhang B. Topological Chern vectors in three-dimensional photonic crystals. Nature 2022; 609:925-930. [PMID: 36171386 DOI: 10.1038/s41586-022-05077-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Accepted: 07/06/2022] [Indexed: 02/01/2023]
Abstract
The paradigmatic example of a topological phase of matter, the two-dimensional Chern insulator1-5, is characterized by a topological invariant consisting of a single integer, the scalar Chern number. Extending the Chern insulator phase from two to three dimensions requires generalization of the Chern number to a three-vector6,7, similar to the three-dimensional (3D) quantum Hall effect8-13. Such Chern vectors for 3D Chern insulators have never been explored experimentally. Here we use magnetically tunable 3D photonic crystals to achieve the experimental demonstration of Chern vectors and their topological surface states. We demonstrate Chern vector magnitudes of up to six, higher than all scalar Chern numbers previously realized in topological materials. The isofrequency contours formed by the topological surface states in the surface Brillouin zone form torus knots or links, whose characteristic integers are determined by the Chern vectors. We demonstrate a sample with surface states forming a (2, 2) torus link or Hopf link in the surface Brillouin zone, which is topologically distinct from the surface states of other 3D topological phases. These results establish the Chern vector as an intrinsic bulk topological invariant in 3D topological materials, with surface states possessing unique topological characteristics.
Collapse
Affiliation(s)
- Gui-Geng Liu
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore
| | - Zhen Gao
- Department of Electronic and Electrical Engineering, Southern University of Science and Technology, Shenzhen, China
| | - Qiang Wang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore
| | - Xiang Xi
- Department of Electronic and Electrical Engineering, Southern University of Science and Technology, Shenzhen, China
| | - Yuan-Hang Hu
- National Engineering Research Center of Electromagnetic Radiation Control Materials, Key Laboratory of Multi-spectral Absorbing Materials and Structures of Ministry of Education, University of Electronic Science and Technology of China, Chengdu, China
| | - Maoren Wang
- National Engineering Research Center of Electromagnetic Radiation Control Materials, Key Laboratory of Multi-spectral Absorbing Materials and Structures of Ministry of Education, University of Electronic Science and Technology of China, Chengdu, China
| | - Chengqi Liu
- National Engineering Research Center of Electromagnetic Radiation Control Materials, Key Laboratory of Multi-spectral Absorbing Materials and Structures of Ministry of Education, University of Electronic Science and Technology of China, Chengdu, China
| | - Xiao Lin
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, ZJU-Hangzhou Global Science and Technology Innovation Center, College of Information Science and Electronic Engineering, ZJU-UIUC Institute, Zhejiang University, Hangzhou, China
| | - Longjiang Deng
- National Engineering Research Center of Electromagnetic Radiation Control Materials, Key Laboratory of Multi-spectral Absorbing Materials and Structures of Ministry of Education, University of Electronic Science and Technology of China, Chengdu, China
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore, Singapore
| | - Peiheng Zhou
- National Engineering Research Center of Electromagnetic Radiation Control Materials, Key Laboratory of Multi-spectral Absorbing Materials and Structures of Ministry of Education, University of Electronic Science and Technology of China, Chengdu, China.
| | - Yihao Yang
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, ZJU-Hangzhou Global Science and Technology Innovation Center, College of Information Science and Electronic Engineering, ZJU-UIUC Institute, Zhejiang University, Hangzhou, China.
| | - Yidong Chong
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore. .,Centre for Disruptive Photonic Technologies, The Photonics Institute, Nanyang Technological University, Singapore, Singapore.
| | - Baile Zhang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore. .,Centre for Disruptive Photonic Technologies, The Photonics Institute, Nanyang Technological University, Singapore, Singapore.
| |
Collapse
|
17
|
Xiao C, Liu H, Wu W, Wang H, Niu Q, Yang SA. Intrinsic Nonlinear Electric Spin Generation in Centrosymmetric Magnets. Phys Rev Lett 2022; 129:086602. [PMID: 36053706 DOI: 10.1103/physrevlett.129.086602] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2022] [Revised: 06/14/2022] [Accepted: 08/03/2022] [Indexed: 06/15/2023]
Abstract
We propose an intrinsic nonlinear electric spin generation effect, which can dominate in centrosymmetric magnets. We reveal the band geometric origin of this effect and clarify its symmetry characters. As an intrinsic effect, it is determined solely by the material's band structure and represents a material characteristic. Combining our theory with first-principle calculations, we predict sizable nonlinear spin generation in single-layer MnBi_{2}Te_{4}, which can be detected in experiment. Our theory opens a new route for all-electric controlled spintronics in centrosymmetric magnets which reside outside of the current paradigm based on linear spin response.
Collapse
Affiliation(s)
- Cong Xiao
- Department of Physics, The University of Hong Kong, Hong Kong, China
- HKU-UCAS Joint Institute of Theoretical and Computational Physics at Hong Kong, Hong Kong, China
| | - Huiying Liu
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Weikang Wu
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
- Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education), Shandong University, Jinan, Shandong 250061, China
| | - Hui Wang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Qian Niu
- School of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| |
Collapse
|
18
|
Tian Y, Yang SA, Yan Q, Tian F, Zhao J. [Ovarian primary malignant melanoma complicated with mature teratoma: report of a case]. Zhonghua Bing Li Xue Za Zhi 2022; 51:779-781. [PMID: 35922176 DOI: 10.3760/cma.j.cn112151-20211116-00831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Affiliation(s)
- Y Tian
- Department of Pathology, Gansu Maternity and Child Health Care Hospital, Lanzhou 730050, China
| | - S A Yang
- Department of Pathology, Gansu Maternity and Child Health Care Hospital, Lanzhou 730050, China
| | - Q Yan
- Department of Pathology, Gansu Maternity and Child Health Care Hospital, Lanzhou 730050, China
| | - F Tian
- Department of Pathology, Gansu Maternity and Child Health Care Hospital, Lanzhou 730050, China
| | - J Zhao
- Department of Pathology, Gansu Maternity and Child Health Care Hospital, Lanzhou 730050, China
| |
Collapse
|
19
|
Lu Q, Cook J, Zhang X, Chen KY, Snyder M, Nguyen DT, Reddy PVS, Qin B, Zhan S, Zhao LD, Kowalczyk PJ, Brown SA, Chiang TC, Yang SA, Chang TR, Bian G. Realization of unpinned two-dimensional dirac states in antimony atomic layers. Nat Commun 2022; 13:4603. [PMID: 35933407 PMCID: PMC9357080 DOI: 10.1038/s41467-022-32327-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Accepted: 07/26/2022] [Indexed: 11/24/2022] Open
Abstract
Two-dimensional (2D) Dirac states with linear dispersion have been observed in graphene and on the surface of topological insulators. 2D Dirac states discovered so far are exclusively pinned at high-symmetry points of the Brillouin zone, for example, surface Dirac states at \documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\overline{{{\Gamma }}}$$\end{document}Γ¯ in topological insulators Bi2Se(Te)3 and Dirac cones at K and \documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$K^{\prime}$$\end{document}K′ points in graphene. The low-energy dispersion of those Dirac states are isotropic due to the constraints of crystal symmetries. In this work, we report the observation of novel 2D Dirac states in antimony atomic layers with phosphorene structure. The Dirac states in the antimony films are located at generic momentum points. This unpinned nature enables versatile ways such as lattice strains to control the locations of the Dirac points in momentum space. In addition, dispersions around the unpinned Dirac points are highly anisotropic due to the reduced symmetry of generic momentum points. The exotic properties of unpinned Dirac states make antimony atomic layers a new type of 2D Dirac semimetals that are distinct from graphene. In graphene and on the surfaces of many topological insulators, the Dirac cones are pinned to high symmetry points in reciprocal space. Here, the authors report that the Dirac cones in atomically-thin Sb layers occur at generic reciprocal-space points which can be tuned by lattice strain.
Collapse
Affiliation(s)
- Qiangsheng Lu
- Department of Physics and Astronomy, University of Missouri, Columbia, MO, 65211, USA
| | - Jacob Cook
- Department of Physics and Astronomy, University of Missouri, Columbia, MO, 65211, USA
| | - Xiaoqian Zhang
- Department of Physics and Astronomy, University of Missouri, Columbia, MO, 65211, USA
| | - Kyle Y Chen
- Rock Bridge High School, Columbia, MO, 65203, USA
| | - Matthew Snyder
- Department of Physics and Astronomy, University of Missouri, Columbia, MO, 65211, USA
| | - Duy Tung Nguyen
- Department of Physics and Astronomy, University of Missouri, Columbia, MO, 65211, USA
| | | | - Bingchao Qin
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Shaoping Zhan
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Li-Dong Zhao
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Pawel J Kowalczyk
- Department of Solid State Physics, Faculty of Physics and Applied Informatics, University of Lodz, 90-236 Lodz, Pomorska, 149/153, Poland.
| | - Simon A Brown
- The MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Physical and Chemical Sciences, University of Canterbury, Private Bag 4800, Christchurch, 8140, New Zealand
| | - Tai-Chang Chiang
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, 61801-3080, USA.,Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, 104 South Goodwin Avenue, Urbana, IL, 61801-2902, USA
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore, 487372, Singapore
| | - Tay-Rong Chang
- Department of Physics, National Cheng Kung University, Tainan, 701, Taiwan
| | - Guang Bian
- Department of Physics and Astronomy, University of Missouri, Columbia, MO, 65211, USA.
| |
Collapse
|
20
|
Guo Y, Yu X, Zhang Y, Zhang X, Yuan S, Li Y, Yang SA, Wang J. 2D Multiferroicity with Ferroelectric Switching Induced Spin-Constrained Photoelectricity. ACS Nano 2022; 16:11174-11181. [PMID: 35816175 DOI: 10.1021/acsnano.2c04017] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Multiferroic materials with tunable magnetoelectric orders enable the integration of sensing, data storage, and processing into one single device. The scarcity of single-phase multiferroics spurs extensive research in pursuit of composite systems combining different types of ferroic materials. In this work, spin-constrained photoelectric memory is proposed in two-dimensional (2D) layered magnetic/ferroelectric heterostructures, holding the possibility of low-power electrical write operation and nondestructive optical read operation. The ground state of ferromagnetic (FM) and antiferromagnetic (AFM) orderings in the magnetic layer is altered by polarization direction of the ferroelectric layer. Specifically, the FM heterostructure exhibits a type-II band alignment. Due to the light-induced charge transfer, spin-polarized/unpolarized current arises from the FM/AFM state, which can be recorded as the "1"/"0" state and served for logic processing and memory applications. Our first-principles calculations demonstrate that the NiI2/In2Se3 heterobilayer is an ideal candidate to realize such a spin-dependent photoelectric memory. The reversible FM state (easy-axis magnetic anisotropy) and AFM state (easy-plane magnetic orientation) in the NiI2 layer originate from interfacial charge transfer and effective electric field due to the proximity effect. This work offers considerable potential in the integration of memory processing capability into one single device with 2D layered multiferroic heterostructures.
Collapse
Affiliation(s)
- Yilv Guo
- School of Physics, Southeast University, Nanjing 211189, China
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Xing Yu
- School of Physics, Southeast University, Nanjing 211189, China
| | - Yehui Zhang
- School of Physics, Southeast University, Nanjing 211189, China
| | - Xiwen Zhang
- School of Mechanism Engineering & School of Physics, Southeast University, Nanjing 211189, China
| | - Shijun Yuan
- School of Physics, Southeast University, Nanjing 211189, China
| | - Yafei Li
- Jiangsu Collaborative Innovation Centre of Biomedical Functional Materials, Jiangsu Key Laboratory of New Power Batteries, School of Chemistry and Material Science, Nanjing Normal University, Nanjing 210023, China
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Jinlan Wang
- School of Physics, Southeast University, Nanjing 211189, China
| |
Collapse
|
21
|
Li Q, Trang CX, Wu W, Hwang J, Cortie D, Medhekar N, Mo SK, Yang SA, Edmonds MT. Large Magnetic Gap in a Designer Ferromagnet-Topological Insulator-Ferromagnet Heterostructure. Adv Mater 2022; 34:e2107520. [PMID: 35261089 DOI: 10.1002/adma.202107520] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 03/03/2022] [Indexed: 06/14/2023]
Abstract
Combining magnetism and nontrivial band topology gives rise to quantum anomalous Hall (QAH) insulators and exotic quantum phases such as the QAH effect where current flows without dissipation along quantized edge states. Inducing magnetic order in topological insulators via proximity to a magnetic material offers a promising pathway toward achieving the QAH effect at a high temperature for lossless transport applications. One promising architecture involves a sandwich structure comprising two single-septuple layers (1SL) of MnBi2 Te4 (a 2D ferromagnetic insulator) with ultrathin few quintuple layer (QL) Bi2 Te3 in the middle, and it is predicted to yield a robust QAH insulator phase with a large bandgap greater than 50 meV. Here, the growth of a 1SL MnBi2 Te4 /4QL Bi2 Te3 /1SL MnBi2 Te4 heterostructure via molecular beam epitaxy is demonstrated and the electronic structure probed using angle-resolved photoelectron spectroscopy. Strong hexagonally warped massive Dirac fermions and a bandgap of 75 ± 15 meV are observed. The magnetic origin of the gap is confirmed by the observation of the exchange-Rashba effect, as well as the vanishing bandgap above the Curie temperature, in agreement with density functional theory calculations. These findings provide insights into magnetic proximity effects in topological insulators and reveal a promising platform for realizing the QAH effect at elevated temperatures.
Collapse
Affiliation(s)
- Qile Li
- School of Physics and Astronomy, Monash University, Clayton, VIC, 3800, Australia
- ARC Centre for Future Low Energy Electronics Technologies, Monash University, Clayton, VIC, 3800, Australia
- Department of Materials Science and Engineering, Monash University, Clayton, VIC, 3800, Australia
| | - Chi Xuan Trang
- School of Physics and Astronomy, Monash University, Clayton, VIC, 3800, Australia
- ARC Centre for Future Low Energy Electronics Technologies, Monash University, Clayton, VIC, 3800, Australia
| | - Weikang Wu
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore, 487372, Singapore
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
| | - Jinwoong Hwang
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - David Cortie
- Australian Nuclear Science and Technology Organization, Lucas Heights, NSW, 2234, Australia
- Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - Nikhil Medhekar
- ARC Centre for Future Low Energy Electronics Technologies, Monash University, Clayton, VIC, 3800, Australia
- Department of Materials Science and Engineering, Monash University, Clayton, VIC, 3800, Australia
| | - Sung-Kwan Mo
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore, 487372, Singapore
| | - Mark T Edmonds
- School of Physics and Astronomy, Monash University, Clayton, VIC, 3800, Australia
- ARC Centre for Future Low Energy Electronics Technologies, Monash University, Clayton, VIC, 3800, Australia
| |
Collapse
|
22
|
Hao X, Wu W, Zhu J, Song B, Meng Q, Wu M, Hua C, Yang SA, Zhou M. Topological band transition between hexagonal and triangular lattices with ( px, py) orbitals. J Phys Condens Matter 2022; 34:255504. [PMID: 35381579 DOI: 10.1088/1361-648x/ac6473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Accepted: 04/05/2022] [Indexed: 06/14/2023]
Abstract
By combining tight-binding modelling with density functional theory based first-principles calculations, we investigate the band evolution of two-dimensional (2D) hexagonal lattices with (px,py) orbitals, focusing on the electronic structures and topological phase transitions. The (px,py)-orbital hexagonal lattice model possesses two flat bands encompassing two linearly dispersive Dirac bands. Breaking the A/B sublattice symmetry could transform the model into two triangular lattices, each featuring a flat band and a dispersive band. Inclusion of the spin-orbit coupling and magnetization may give rise to quantum spin Hall and quantum anomalous Hall (QAH) states. As a proof of concept, we demonstrate that half-hydrogenated stanene is encoded by a triangular lattice with (px,py) orbitals, which exhibits ferromagnetism and QAH effect with a topological gap of ∼0.15 eV, feasible for experimental observation. These results provide insights into the structure-property relationships involving the orbital degree of freedom, which may shed light on future design and preparation of 2D topological materials for novel electronic/spintronic and quantum computing devices.
Collapse
Affiliation(s)
- Xiamin Hao
- School of Physics, Beihang University, Beijing 100191, People's Republic of China
- Beihang Hangzhou Innovation Institute Yuhang, Hangzhou 310023, People's Republic of China
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Weikang Wu
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Jiaojiao Zhu
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Biyu Song
- School of Physics, Beihang University, Beijing 100191, People's Republic of China
- Beihang Hangzhou Innovation Institute Yuhang, Hangzhou 310023, People's Republic of China
| | - Qingling Meng
- School of Physics, Beihang University, Beijing 100191, People's Republic of China
- Beihang Hangzhou Innovation Institute Yuhang, Hangzhou 310023, People's Republic of China
| | - Meimei Wu
- Beihang Hangzhou Innovation Institute Yuhang, Hangzhou 310023, People's Republic of China
| | - Chenqiang Hua
- Beihang Hangzhou Innovation Institute Yuhang, Hangzhou 310023, People's Republic of China
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Miao Zhou
- School of Physics, Beihang University, Beijing 100191, People's Republic of China
- Beihang Hangzhou Innovation Institute Yuhang, Hangzhou 310023, People's Republic of China
| |
Collapse
|
23
|
Xue H, Wang Z, Huang YX, Cheng Z, Yu L, Foo YX, Zhao YX, Yang SA, Zhang B. Projectively Enriched Symmetry and Topology in Acoustic Crystals. Phys Rev Lett 2022; 128:116802. [PMID: 35363008 DOI: 10.1103/physrevlett.128.116802] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Accepted: 01/27/2022] [Indexed: 06/14/2023]
Abstract
Symmetry plays a key role in modern physics, as manifested in the revolutionary topological classification of matter in the past decade. So far, we seem to have a complete theory of topological phases from internal symmetries as well as crystallographic symmetry groups. However, an intrinsic element, i.e., the gauge symmetry in physical systems, has been overlooked in the current framework. Here, we show that the algebraic structure of crystal symmetries can be projectively enriched due to the gauge symmetry, which subsequently gives rise to new topological physics never witnessed under ordinary symmetries. We demonstrate the idea by theoretical analysis, numerical simulation, and experimental realization of a topological acoustic lattice with projective translation symmetries under a Z_{2} gauge field, which exhibits unique features of rich topologies, including a single Dirac point, Möbius topological insulator, and graphenelike semimetal phases on a rectangular lattice. Our work reveals the impact when gauge and crystal symmetries meet together with topology and opens the door to a vast unexplored land of topological states by projective symmetries.
Collapse
Affiliation(s)
- Haoran Xue
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Zihao Wang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Yue-Xin Huang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Zheyu Cheng
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Letian Yu
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Y X Foo
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Y X Zhao
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Baile Zhang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- Centre for Disruptive Photonic Technologies, Nanyang Technological University, Singapore 637371, Singapore
| |
Collapse
|
24
|
Tao S, Zhang X, Zhu J, He P, Yang SA, Lu Y, Wei SH. Designing Ultra-flat Bands in Twisted Bilayer Materials at Large Twist Angles: Theory and Application to Two-Dimensional Indium Selenide. J Am Chem Soc 2022; 144:3949-3956. [PMID: 35200018 DOI: 10.1021/jacs.1c11953] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Intertwisted bilayers of two-dimensional (2D) materials can host low-energy flat bands, which offer opportunity to investigate many intriguing physics associated with strong electron correlations. In the existing systems, ultra-flat bands only emerge at very small twist angles less than a few degrees, which poses a challenge for experimental studies and practical applications. Here, we propose a new design principle to achieve low-energy ultra-flat bands with increased twist angles. The key condition is to have a 2D semiconducting material with a large energy difference of band edges controlled by stacking. We show that the interlayer interaction leads to defect-like states under twisting, which forms a flat band in the semiconducting band gap with dispersion strongly suppressed by the large energy barriers in the moiré superlattice even for large twist angles. We explicitly demonstrate our idea in bilayer α-In2Se3 and bilayer InSe. For bilayer α-In2Se3, we show that a twist angle of ∼13.2° is sufficient to achieve the band flatness comparable to that of twist bilayer graphene at the magic angle ∼1.1°. In addition, the appearance of ultra-flat bands here is not sensitive to the twist angle as in bilayer graphene, and it can be further controlled by external gate fields. Our finding provides a new route to achieve ultra-flat bands other than reducing the twist angles and paves the way toward engineering such flat bands in a large family of 2D materials.
Collapse
Affiliation(s)
- Shengdan Tao
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou 310027, China
| | - Xuanlin Zhang
- State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Jiaojiao Zhu
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Pimo He
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou 310027, China
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Yunhao Lu
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou 310027, China.,State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Su-Huai Wei
- Beijing Computational Science Research Center, Beijing 100193, China
| |
Collapse
|
25
|
Abstract
The diode effect means that carriers can only flow in one direction but not the other. While diode effects for electron charge, spin, or photon have been widely discussed, it remains a question whether a chiral phonon diode can be realized, which utilizes the chiral degree of freedom of lattice vibrations. In this work, we reveal an intrinsic connection between the chiralities of a crystal structure and its phonon excitations, which naturally leads to the chiral phonon diode effect in chiral crystals. At a certain frequency, phonons with a definite chirality can propagate only in one direction but not the opposite. We demonstrate the idea in concrete materials including bulk Te and α-quartz (SiO2). Our work discovers the fundamental physics of chirality coupling between different levels of a system, and the predicted effect will provide a new route to control phonon transport and design information devices.
Collapse
Affiliation(s)
- Hao Chen
- NNU-SULI Thermal Energy Research Center and Center for Quantum Transport and Thermal Energy Science (CQTES), School of Physics and Technology, Nanjing Normal University, Nanjing 210023, China
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Weikang Wu
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Jiaojiao Zhu
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Zhengning Yang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Weikang Gong
- College of Life Science and Chemistry, Faculty of Environmental and Life Sciences, Beijing University of Technology, Beijing 100124, China
- Division of Mathematical Sciences, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Weibo Gao
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Lifa Zhang
- NNU-SULI Thermal Energy Research Center and Center for Quantum Transport and Thermal Energy Science (CQTES), School of Physics and Technology, Nanjing Normal University, Nanjing 210023, China
| |
Collapse
|
26
|
Wang C, Xiao RC, Liu H, Zhang Z, Lai S, Zhu C, Cai H, Wang N, Chen S, Deng Y, Liu Z, Yang SA, Gao WB. Room-temperature third-order nonlinear Hall effect in Weyl semimetal TaIrTe 4. Natl Sci Rev 2022; 9:nwac020. [PMID: 36694799 PMCID: PMC9869080 DOI: 10.1093/nsr/nwac020] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 01/14/2022] [Accepted: 01/16/2022] [Indexed: 01/27/2023] Open
Abstract
The second-order nonlinear Hall effect observed in the time-reversal symmetric system has not only shown abundant physical content, but also exhibited potential application prospects. Recently, a third-order nonlinear Hall effect has been observed in MoTe2 and WTe2. However, few-layer MoTe2 and WTe2 are usually unstable in air and the observed third-order nonlinear Hall effect can be measured only at low temperature, which hinders further investigation as well as potential application. Thus, exploring new air-stable material systems with a sizable third-order nonlinear Hall effect at room temperature is an urgent task. Here, in type-II Weyl semimetal TaIrTe4, we observed a pronounced third-order nonlinear Hall effect, which can exist at room temperature and remain stable for months. The third-order nonlinear Hall effect is connected to the Berry-connection polarizability tensor instead of the Berry curvature. The possible mechanism of the observation of the third-order nonlinear Hall effect in TaIrTe4 at room temperature has been discussed. Our findings will open an avenue towards exploring room-temperature nonlinear devices in new quantum materials.
Collapse
Affiliation(s)
| | | | - Huiying Liu
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore487372, Singapore
| | - Zhaowei Zhang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore637371, Singapore
| | - Shen Lai
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore637371, Singapore
| | - Chao Zhu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore639798, Singapore
| | - Hongbing Cai
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore637371, Singapore
| | - Naizhou Wang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore637371, Singapore
| | - Shengyao Chen
- CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing100190, China
| | - Ya Deng
- School of Materials Science and Engineering, Nanyang Technological University, Singapore639798, Singapore
| | - Zheng Liu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore639798, Singapore
| | | | | |
Collapse
|
27
|
Chen C, Zeng XT, Chen Z, Zhao YX, Sheng XL, Yang SA. Second-Order Real Nodal-Line Semimetal in Three-Dimensional Graphdiyne. Phys Rev Lett 2022; 128:026405. [PMID: 35089745 DOI: 10.1103/physrevlett.128.026405] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 11/11/2021] [Accepted: 12/21/2021] [Indexed: 06/14/2023]
Abstract
Real topological phases featuring real Chern numbers and second-order boundary modes have been a focus of current research, but finding their material realization remains a challenge. Here, based on first-principles calculations and theoretical analysis, we reveal the already experimentally synthesized three-dimensional (3D) graphdiyne as the first realistic example of the recently proposed second-order real nodal-line semimetal. We show that the material hosts a pair of real nodal rings, each protected by two topological charges: a real Chern number and a 1D winding number. The two charges generate distinct topological boundary modes at distinct boundaries. The real Chern number leads to a pair of hinge Fermi arcs, whereas the winding number protects a double drumhead surface bands. We develop a low-energy model for 3D graphdiyne which captures the essential topological physics. Experimental aspects and possible topological transition to a 3D real Chern insulator phase are discussed.
Collapse
Affiliation(s)
- Cong Chen
- School of Physics, Beihang University, Beijing 100191, China
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Xu-Tao Zeng
- School of Physics, Beihang University, Beijing 100191, China
| | - Ziyu Chen
- School of Physics, Beihang University, Beijing 100191, China
| | - Y X Zhao
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Xian-Lei Sheng
- School of Physics, Beihang University, Beijing 100191, China
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| |
Collapse
|
28
|
Liu H, Zhao J, Huang YX, Wu W, Sheng XL, Xiao C, Yang SA. Intrinsic Second-Order Anomalous Hall Effect and Its Application in Compensated Antiferromagnets. Phys Rev Lett 2021; 127:277202. [PMID: 35061417 DOI: 10.1103/physrevlett.127.277202] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2021] [Accepted: 11/23/2021] [Indexed: 06/14/2023]
Abstract
Response properties that are purely intrinsic to physical systems are of paramount importance in physics research, as they probe fundamental properties of band structures and allow quantitative calculation and comparison with experiment. For anomalous Hall transport in magnets, an intrinsic effect can appear at the second order to the applied electric field. We show that this intrinsic second-order anomalous Hall effect is associated with an intrinsic band geometric property-the dipole moment of Berry-connection polarizability (BCP) in momentum space. The effect has scaling relation and symmetry constraints that are distinct from the previously studied extrinsic contributions. Particularly, in antiferromagnets with PT symmetry, the intrinsic effect dominates. Combined with first-principles calculations, we demonstrate the first quantitative evaluation of the effect in the antiferromagnet Mn_{2}Au. We show that the BCP dipole and the resulting intrinsic second-order conductivity are pronounced around band near degeneracies. Importantly, the intrinsic response exhibits sensitive dependence on the Néel vector orientation with a 2π periodicity, which offers a new route for electric detection of the magnetic order in PT-invariant antiferromagnets.
Collapse
Affiliation(s)
- Huiying Liu
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Jianzhou Zhao
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
- Co-Innovation Center for New Energetic Materials, Southwest University of Science and Technology, Mianyang 621010, China
| | - Yue-Xin Huang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Weikang Wu
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Xian-Lei Sheng
- School of Physics, Beihang University, Beijing 100191, China
| | - Cong Xiao
- Department of Physics, The University of Hong Kong, Hong Kong, China
- HKU-UCAS Joint Institute of Theoretical and Computational Physics, Hong Kong, China
- Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| |
Collapse
|
29
|
Shao LB, Liu Q, Xiao R, Yang SA, Zhao YX. Gauge-Field Extended k·p Method and Novel Topological Phases. Phys Rev Lett 2021; 127:076401. [PMID: 34459642 DOI: 10.1103/physrevlett.127.076401] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 07/01/2021] [Indexed: 06/13/2023]
Abstract
Although topological artificial systems, like acoustic and photonic crystals and cold atoms in optical lattices were initially motivated by simulating topological phases of electronic systems, they have their own unique features such as the spinless time-reversal symmetry and tunable Z_{2} gauge fields. Hence, it is fundamentally important to explore new topological phases based on these features. Here, we point out that the Z_{2} gauge field leads to two fundamental modifications of the conventional k·p method: (i) The little co-group must include the translations with nontrivial algebraic relations. (ii) The algebraic relations of the little co-group are projectively represented. These give rise to higher-dimensional irreducible representations and therefore highly degenerate Fermi points. Breaking the primitive translations can transform the Fermi points to interesting topological phases. We demonstrate our theory by two models: a rectangular π-flux model exhibiting graphenelike semimetal phases, and a graphite model with interlayer π flux that realizes the real second-order nodal-line semimetal phase with hinge helical modes. Their physical realizations with a general bright-dark mechanism are discussed. Our finding opens a new direction to explore novel topological phases unique to crystalline systems with gauge fields and establishes the approach to analyze these phases.
Collapse
Affiliation(s)
- L B Shao
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Q Liu
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - R Xiao
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Y X Zhao
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| |
Collapse
|
30
|
Lai S, Liu H, Zhang Z, Zhao J, Feng X, Wang N, Tang C, Liu Y, Novoselov KS, Yang SA, Gao WB. Third-order nonlinear Hall effect induced by the Berry-connection polarizability tensor. Nat Nanotechnol 2021; 16:869-873. [PMID: 34168343 DOI: 10.1038/s41565-021-00917-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 04/26/2021] [Indexed: 06/13/2023]
Abstract
Nonlinear responses in transport measurements are linked to material properties not accessible at linear order1 because they follow distinct symmetry requirements2-5. While the linear Hall effect indicates time-reversal symmetry breaking, the second-order nonlinear Hall effect typically requires broken inversion symmetry1. Recent experiments on ultrathin WTe2 demonstrated this connection between crystal structure and nonlinear response6,7. The observed second-order nonlinear Hall effect can probe the Berry curvature dipole, a band geometric property, in non-magnetic materials, just like the anomalous Hall effect probes the Berry curvature in magnetic materials8,9. Theory predicts that another intrinsic band geometric property, the Berry-connection polarizability tensor10, gives rise to higher-order signals, but it has not been probed experimentally. Here, we report a third-order nonlinear Hall effect in thick Td-MoTe2 samples. The third-order signal is found to be the dominant response over both the linear- and second-order ones. Angle-resolved measurements reveal that this feature results from crystal symmetry constraints. Temperature-dependent measurement shows that the third-order Hall response agrees with the Berry-connection polarizability contribution evaluated by first-principles calculations. The third-order nonlinear Hall effect provides a valuable probe for intriguing material properties that are not accessible at lower orders and may be employed for high-order-response electronic devices.
Collapse
Affiliation(s)
- Shen Lai
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore
| | - Huiying Liu
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore, Singapore
| | - Zhaowei Zhang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore
| | - Jianzhou Zhao
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore, Singapore
| | - Xiaolong Feng
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore, Singapore
| | - Naizhou Wang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore
| | - Chaolong Tang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore
| | - Yuanda Liu
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore
| | - K S Novoselov
- Department of Material Science & Engineering, National University of Singapore, Singapore, Singapore.
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore, Singapore.
| | - Wei-Bo Gao
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore.
- The Photonics Institute and Centre for Disruptive Photonic Technologies, Nanyang Technological University, Singapore, Singapore.
| |
Collapse
|
31
|
Tan Q, Rasmita A, Li S, Liu S, Huang Z, Xiong Q, Yang SA, Novoselov KS, Gao WB. Layer-engineered interlayer excitons. Sci Adv 2021; 7:7/30/eabh0863. [PMID: 34301603 PMCID: PMC8302131 DOI: 10.1126/sciadv.abh0863] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 06/07/2021] [Indexed: 05/21/2023]
Abstract
Photoluminescence (PL) from excitons serves as a powerful tool to characterize the optoelectronic property and band structure of semiconductors, especially for atomically thin two-dimensional transition metal dichalcogenide (TMD) materials. However, PL quenches quickly when the thickness of TMD materials increases from monolayer to a few layers, due to the change from direct to indirect band transition. Here, we show that PL can be recovered by engineering multilayer heterostructures, with the band transition reserved to be a direct type. We report emission from layer-engineered interlayer excitons from these multilayer heterostructures. Moreover, as desired for valleytronics devices, the lifetime, valley polarization, and valley lifetime of the generated interlayer excitons can all be substantially improved as compared with that in the monolayer-monolayer heterostructure. Our results pave the way for controlling the properties of interlayer excitons by layer engineering.
Collapse
Affiliation(s)
- Qinghai Tan
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Abdullah Rasmita
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Si Li
- Research Laboratory for Quantum Materials in Singapore University of Technology and Design, Singapore 487372, Singapore
- School of Physics, Northwest University, Xi' an 710069, China
| | - Sheng Liu
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Zumeng Huang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Qihua Xiong
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing, China
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials in Singapore University of Technology and Design, Singapore 487372, Singapore.
| | - K S Novoselov
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117575, Singapore.
| | - Wei-Bo Gao
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore.
- The Photonics Institute and Centre for Disruptive Photonic Technologies, Nanyang Technological University, Singapore 637371, Singapore
| |
Collapse
|
32
|
Huang M, Wang S, Wang Z, Liu P, Xiang J, Feng C, Wang X, Zhang Z, Wen Z, Xu H, Yu G, Lu Y, Zhao W, Yang SA, Hou D, Xiang B. Colossal Anomalous Hall Effect in Ferromagnetic van der Waals CrTe 2. ACS Nano 2021; 15:9759-9763. [PMID: 33881844 DOI: 10.1021/acsnano.1c00488] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
van der Waals crystals exhibit excellent material performance when exfoliated to few-atomic-layer thickness. In contrast, the van der Waals thin films more than 10 nm thick are believed to show bulk properties, in which outstanding material performance is rarely found. Here we report the largest anomalous Hall conductivity observed so far in a 170 nm van der Waals ferromagnetic 1T-CrTe2 flake, which reaches 67,000 Ω-1 cm-1. Such a colossal anomalous Hall conductivity in 1T-CrTe2 is dominated by the extrinsic skew scattering process rather than the intrinsic Berry phase effect, as evidenced by the linear relation between the anomalous Hall conductivity and the longitudinal conductivity. Defying the dilemma of mutually exclusive large anomalous Hall angle and high electric conductivity for most ferromagnets, 1T-CrTe2 achieves both in a thin film sample. Considering the shared physics of the anomalous Hall effect and the spin Hall effect, our finding offers a guideline for searching large spin Hall materials of high conductivity which may overcome the bottleneck of overheating in spintronics devices.
Collapse
Affiliation(s)
- Meng Huang
- Hefei National Research Center for Physical Sciences at the Microscale, International Centre for Quantum Design of Functional Materials, Department of Materials Science & Engineering, CAS Key Lab of Materials for Energy Conversion, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Shanshan Wang
- School of Physics, Southeast University, Nanjing 211189, China
| | - Zhaohao Wang
- Fert Beijing Institute, BDBC, and School of Microelectronics, Beihang University, Beijing 100191, China
| | - Ping Liu
- Hefei National Research Center for Physical Sciences at the Microscale, International Centre for Quantum Design of Functional Materials, Department of Materials Science & Engineering, CAS Key Lab of Materials for Energy Conversion, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Junxiang Xiang
- Hefei National Research Center for Physical Sciences at the Microscale, International Centre for Quantum Design of Functional Materials, Department of Materials Science & Engineering, CAS Key Lab of Materials for Energy Conversion, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Chao Feng
- Hefei National Research Center for Physical Sciences at the Microscale, International Centre for Quantum Design of Functional Materials, Department of Materials Science & Engineering, CAS Key Lab of Materials for Energy Conversion, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Xiangqi Wang
- Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Zengming Zhang
- The Centre for Physical Experiments, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Zhenchao Wen
- National Institute for Materials Science (NIMS), Tsukuba 304-0047, Japan
| | - Hongjun Xu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China
| | - Guoqiang Yu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China
| | - Yalin Lu
- Hefei National Research Center for Physical Sciences at the Microscale, International Centre for Quantum Design of Functional Materials, Department of Materials Science & Engineering, CAS Key Lab of Materials for Energy Conversion, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Weisheng Zhao
- Fert Beijing Institute, BDBC, and School of Microelectronics, Beihang University, Beijing 100191, China
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Dazhi Hou
- Hefei National Research Center for Physical Sciences at the Microscale, International Centre for Quantum Design of Functional Materials, Department of Materials Science & Engineering, CAS Key Lab of Materials for Energy Conversion, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Bin Xiang
- Hefei National Research Center for Physical Sciences at the Microscale, International Centre for Quantum Design of Functional Materials, Department of Materials Science & Engineering, CAS Key Lab of Materials for Energy Conversion, University of Science and Technology of China, Hefei, Anhui 230026, China
| |
Collapse
|
33
|
Lodge MS, Yang SA, Mukherjee S, Weber B. Atomically Thin Quantum Spin Hall Insulators. Adv Mater 2021; 33:e2008029. [PMID: 33893669 DOI: 10.1002/adma.202008029] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 01/12/2021] [Indexed: 06/12/2023]
Abstract
Atomically thin topological materials are attracting growing attention for their potential to radically transform classical and quantum electronic device concepts. Among them is the quantum spin Hall (QSH) insulator-a 2D state of matter that arises from interplay of topological band inversion and strong spin-orbit coupling, with large tunable bulk bandgaps up to 800 meV and gapless, 1D edge states. Reviewing recent advances in materials science and engineering alongside theoretical description, the QSH materials library is surveyed with focus on the prospects for QSH-based device applications. In particular, theoretical predictions of nontrivial superconducting pairing in the QSH state toward Majorana-based topological quantum computing are discussed, which are the next frontier in QSH materials research.
Collapse
Affiliation(s)
- Michael S Lodge
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore, 487372, Singapore
| | - Shantanu Mukherjee
- Department of Physics, Indian Institute of Technology Madras, Chennai, Tamil Nadu, 600036, India
- Quantum Centres in Diamond and Emergent Materials (QCenDiem)-Group, IIT Madras, Chennai, Tamil Nadu, 600036, India
- Computational Materials Science Group, IIT Madras, Chennai, Tamil Nadu, 600036, India
| | - Bent Weber
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
- Australian Research Council (ARC) Centre of Excellence in Future Low-Energy Electronics Techonologies (FLEET), School of Physics, Monash University, Clayton, VIC, 3800, Australia
| |
Collapse
|
34
|
Liu Y, Wang G, Luo F, Li H, Zhu M, Liu X, Yang SA, Liu S. Functional Group-induced p-Doping of MoS 2 by Titanium(IV) Bis(ammonium lactato) Dihydroxide Physisorption. Chem Asian J 2021; 16:1756-1761. [PMID: 33991065 DOI: 10.1002/asia.202100300] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 05/11/2021] [Indexed: 11/09/2022]
Abstract
P-type doping is of critical importance for the realization of certain high-performance electrical and optoelectronic devices based on molybdenum disulfide (MoS2 ). Charge transfer doping is a feasible strategy for tuning the conductance properties via facile treatment. In this work, the electrical properties of few-layer MoS2 were modulated with titanium(IV) bis(ammonium lactato) dihydroxide molecules (denoted as TALH) via physisorption. The functional groups such as electronegative hydroxyl (-OH) and carboxylate groups (-COO) included in TALH molecules are expected to induce p-doping effect through surface charge transfer when being attached to MoS2 . The p-doping is proved by X-ray photoelectron spectroscopy (XPS) with the downshift of Mo 3d and S 2p peaks. Control experiments and density functional theory calculations validate that the p-type doping mainly originated from the -OH group in TALH, which drew electrons from MoS2 . These results suggest that functional group-mediated p-doping effect show a path to modulate the carrier transition in MoS2, and enrich the molecule series for device modification.
Collapse
Affiliation(s)
- Yeru Liu
- Institute of Chemical Biology and Nanomedicine (ICBN), State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, P. R. China
| | - Guangzhao Wang
- School of Electronic Information Engineering, Key Laboratory of Extraordinary Bond Engineering and Advanced Materials Technology of Chongqing, Yangtze Normal University, Chongqing, 408100, P. R. China.,Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore, 487372, Singapore
| | - Fang Luo
- College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha, 410073, P. R. China
| | - Huimin Li
- Institute of Chemical Biology and Nanomedicine (ICBN), State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, P. R. China
| | - Mengjian Zhu
- College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha, 410073, P. R. China
| | - Xiaochi Liu
- School of Physics and Electronics, Hunan Key Laboratory of Super Micro-structure and Ultrafast Process, Central South University, Changsha, 410083, P. R. China
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore, 487372, Singapore
| | - Song Liu
- Institute of Chemical Biology and Nanomedicine (ICBN), State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, P. R. China
| |
Collapse
|
35
|
Yan D, Lim YV, Wang G, Shang Y, Li XL, Fang D, Pam ME, Yang SA, Wang Y, Shi Y, Yang HY. Unlocking Rapid and Robust Sodium Storage Performance of Zinc-Based Sulfide via Indium Incorporation. ACS Nano 2021; 15:8507-8516. [PMID: 33900061 DOI: 10.1021/acsnano.1c00131] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Zinc sulfide (ZnS) exhibits promise in sodium-ion batteries (SIBs) because of its low operation voltage and high theoretical specific capacity. However, pristine ZnS is not adequate in realizing rapid and robust sodium storage owing to its low reversibility, poor structure stability, and sluggish kinetics. To date, most efforts focus on utilizing carbonaceous incorporation to improve its electrochemical performances. Nevertheless, it remains an arduous challenge for realizing superior rate capability while obtaining stable cycling. Herein, inspired by the crystal structure of hexagonal ZnIn2S4, which possesses an intrinsic layered feature with larger unit-cell volume versus that of ZnS, indium incorporation is thus deployed as an immediate remedy. In/ex situ investigations combined with density functional theory calculations are conducted to reveal the superior kinetics, high reversibility, and good structure stability of ZnIn2S4. Notably, the formed indium-based derivatives during cycling manifest a Na+ (de)intercalation process, thereby exciting a synergetic mechanism to stabilize electrochemical cycling. As a result, the electrochemical performances of Zn-based sulfide are significantly improved via the indium incorporation. Furthermore, a full cell based on the ZnIn2S4 anode with the superior electrochemical performance is developed. This work provides an effective tactic of heteroatom incorporation for optimizing structure as well as exciting a complementary reaction process toward developing superior anodes for high-performance alkali-ion batteries.
Collapse
Affiliation(s)
- Dong Yan
- International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, P. R. China
- Pillar of Engineering Product Development, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Yew Von Lim
- Pillar of Engineering Product Development, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Guangzhao Wang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
- Key Laboratory of Extraordinary Bond Engineering and Advanced Materials Technology of Chongqing, School of Electronic Information Engineering, Yangtze Normal University, Chongqing 408100, P. R. China
| | - Yang Shang
- Pillar of Engineering Product Development, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Xue Liang Li
- Pillar of Engineering Product Development, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Daliang Fang
- Pillar of Engineering Product Development, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Mei Er Pam
- Pillar of Engineering Product Development, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Ye Wang
- Key Laboratory of Material Physics of Ministry of Education, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450052, P. R. China
| | - Yumeng Shi
- International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, P. R. China
| | - Hui Ying Yang
- Pillar of Engineering Product Development, Singapore University of Technology and Design, Singapore 487372, Singapore
| |
Collapse
|
36
|
Zhao YX, Chen C, Sheng XL, Yang SA. Switching Spinless and Spinful Topological Phases with Projective PT Symmetry. Phys Rev Lett 2021; 126:196402. [PMID: 34047612 DOI: 10.1103/physrevlett.126.196402] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 01/21/2021] [Accepted: 04/07/2021] [Indexed: 06/12/2023]
Abstract
A fundamental dichotomous classification for all physical systems is according to whether they are spinless or spinful. This is especially crucial for the study of symmetry-protected topological phases, as the two classes have distinct symmetry algebra. As a prominent example, the spacetime inversion symmetry PT satisfies (PT)^{2}=±1 for spinless/spinful systems, and each class features unique topological phases. Here, we reveal a possibility to switch the two fundamental classes via Z_{2} projective representations. For PT symmetry, this occurs when P inverses the gauge transformation needed to recover the original Z_{2} gauge connections under P. As a result, we can achieve topological phases originally unique for spinful systems in a spinless system, and vice versa. We explicitly demonstrate the claimed mechanism with several concrete models, such as Kramers degenerate bands and Kramers Majorana boundary modes in spinless systems, and real topological phases in spinful systems. Possible experimental realization of these models is discussed. Our work breaks a fundamental limitation on topological phases and opens an unprecedented possibility to realize intriguing topological phases in previously impossible systems.
Collapse
Affiliation(s)
- Y X Zhao
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Cong Chen
- School of Physics, and Key Laboratory of Micro-nano Measurement-Manipulation and Physics, Beihang University, Beijing 100191, China
| | - Xian-Lei Sheng
- School of Physics, and Key Laboratory of Micro-nano Measurement-Manipulation and Physics, Beihang University, Beijing 100191, China
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| |
Collapse
|
37
|
Wang B, Xia W, Li S, Wang K, Yang SA, Guo Y, Xue J. One-Dimensional Metal Embedded in Two-Dimensional Semiconductor in Nb 2Si x-1Te 4. ACS Nano 2021; 15:7149-7154. [PMID: 33739831 DOI: 10.1021/acsnano.1c00320] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The ternary van der Waals material Nb2Six-1Te4 demonstrates many interesting properties as the content of Si is changed, ranging from metallic Nb3SiTe6 (x = 5/3) to narrow-gap semiconductor Nb2SiTe4 (x = 2) and with the emergence of one-dimensional Dirac fermion excitations in between. An in-depth understanding of their properties with different stoichiometry is important. Here we use scanning tunneling microscopy and spectroscopy to reveal that Nb2Six-1Te4 is a system with spontaneously developed and self-aligned one-dimensional metallic chains embedded in a two-dimensional semiconductor. Electron quasiparticles form one- and two-dimensional standing waves side by side. This special microscopic structure results in strong transport anisotropy. Along the chain direction the material behaves like a metal, while perpendicular to the chain direction, it behaves like a semiconductor. These findings provide an important basis for further investigation of this intriguing system.
Collapse
Affiliation(s)
- Binbin Wang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wei Xia
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- ShanghaiTech Laboratory for Topological Physics, Shanghai 201210, China
| | - Si Li
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
- School of Physics, Northwest University, Xi'an 710069, China
| | - Kang Wang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Yanfeng Guo
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Jiamin Xue
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| |
Collapse
|
38
|
Abstract
Chiral phonons were initially proposed and experimentally verified in two-dimensional (2D) systems. Their intriguing effects have generated profound impacts on multiple research fields. However, all chiral phonons reported to date are constrained to be local, in the sense that their group velocities vanish identically. Here, we propose the concept of propagating 3D chiral phonons, which can transport the information on chirality and angular momentum. Guided by the necessary conditions and using first-principles calculations, we demonstrate their existence in WN2. The chirality, group velocity, and pseudoangular momentum are analyzed. Based on their selective coupling with valley electrons and photons, we propose an experimental setup to detect the unique feature of propagating chiral phonons. Our work endows chiral phonons with a crucial character-the ability to propagate and transport quantized information, which creates a new research direction and opens up the possibility to design novel phononic quantum devices.
Collapse
Affiliation(s)
- Hao Chen
- NNU-SULI Thermal Energy Research Center and Center for Quantum Transport and Thermal Energy Science (CQTES), School of Physics and Technology, Nanjing Normal University, Nanjing 210023, China
| | - Weikang Wu
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Jiaojiao Zhu
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Lifa Zhang
- NNU-SULI Thermal Energy Research Center and Center for Quantum Transport and Thermal Energy Science (CQTES), School of Physics and Technology, Nanjing Normal University, Nanjing 210023, China
| |
Collapse
|
39
|
Ma F, Jiao Y, Wu W, Liu Y, Yang SA, Heine T. Half-Auxeticity and Anisotropic Transport in Pd Decorated Two-Dimensional Boron Sheets. Nano Lett 2021; 21:2356-2362. [PMID: 33656900 DOI: 10.1021/acs.nanolett.0c04154] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Upon strain, most materials shrink normal to the direction of applied strain. Similarly, if a material is compressed, it will expand in the direction orthogonal to the pressure. Few materials, those of negative Poisson ratio, show the opposite behavior. Here, we show an unprecedented feature, a material that expands normal to the direction of stress, regardless if it is strained or compressed. Such behavior, namely, half-auxeticity, is demonstrated for a borophene sheet stabilized by decorating Pd atoms. We explore Pd-decorated borophene, identify three stable phases of which one has this peculiar property of half auxeticity. After carefully analyzing stability and mechanical and electronic properties we explore the origin of this very uncommon behavior and identify it as a structural feature that may also be employed to design further 2D nanomaterials.
Collapse
Affiliation(s)
- Fengxian Ma
- College of Physics, Hebei Key Laboratory of Photophysics Research and Application, Hebei Normal University, 050024 Shijiazhuang, China
| | - Yalong Jiao
- Faculty for Chemistry and Food Chemistry, TU Dresden, Bergstraße 66c, 01069 Dresden, Germany
| | - Weikang Wu
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, 487372 Singapore, Singapore
| | - Ying Liu
- College of Physics, Hebei Key Laboratory of Photophysics Research and Application, Hebei Normal University, 050024 Shijiazhuang, China
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, 487372 Singapore, Singapore
| | - Thomas Heine
- Faculty for Chemistry and Food Chemistry, TU Dresden, Bergstraße 66c, 01069 Dresden, Germany
- Institute of Resource Ecology, Leipzig Research Branch, Helmholtz-Center Dresden Rossendorf, 04316 Leipzig, Germany
- Department of Chemistry, Yonsei University, 03722 Seoul, Korea
| |
Collapse
|
40
|
Yang C, Chen M, Li S, Zhang X, Hua C, Bai H, Xiao C, Yang SA, He P, Xu ZA, Lu Y. Coexistence of Ferroelectricity and Ferromagnetism in One-Dimensional SbN and BiN Nanowires. ACS Appl Mater Interfaces 2021; 13:13517-13523. [PMID: 33689259 DOI: 10.1021/acsami.0c20570] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Ferroelectricity exists in a variety of three- and two-dimensional materials and is of great significance for the development of electronic devices. However, the presence of ferroelectricity in one-dimensional materials is extremely rare. Here, we predict ferroelectricity in one-dimensional SbN and BiN nanowires. Their polarization strengths are 1 order of magnitude higher than ever reported values in one-dimensional structures. Moreover, we find that spontaneous spin polarization can be generated in SbN and BiN nanowires by moderate hole doping. This is the first time the coexistence of both ferroelectricity and ferromagnetism in a one-dimensional system has been reported. Our finding not only broadens the family of one-dimensional ferroelectric materials but also offers a promising platform for novel electronic and spintronic applications.
Collapse
Affiliation(s)
- Chao Yang
- School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Miaogen Chen
- School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China
- Key Laboratory of Intelligent Manufacturing Quality Big Data Tracing and Analysis of Zhejiang Province, Department of Physics, China Jiliang University, Hangzhou 310018, China
| | - Si Li
- Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education, Department of Physics and Synergetic Innovation Center for Quantum Effects and Applications, Hunan Normal University, Changsha 410081, China
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Xuanlin Zhang
- School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Chenqiang Hua
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou 310027, China
| | - Hua Bai
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou 310027, China
| | - Chengcheng Xiao
- Departments of Materials and Physics, and the Thomas Young Centre for Theory and Simulation of Materials, Imperial College London, London SW7 2 AZ, U.K
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Pimo He
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou 310027, China
| | - Zhu-An Xu
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou 310027, China
| | - Yunhao Lu
- School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou 310027, China
| |
Collapse
|
41
|
Di Bernardo I, Hellerstedt J, Liu C, Akhgar G, Wu W, Yang SA, Culcer D, Mo SK, Adam S, Edmonds MT, Fuhrer MS. Progress in Epitaxial Thin-Film Na 3 Bi as a Topological Electronic Material. Adv Mater 2021; 33:e2005897. [PMID: 33538071 DOI: 10.1002/adma.202005897] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 09/24/2020] [Indexed: 06/12/2023]
Abstract
Trisodium bismuthide (Na3 Bi) is the first experimentally verified topological Dirac semimetal, and is a 3D analogue of graphene hosting relativistic Dirac fermions. Its unconventional momentum-energy relationship is interesting from a fundamental perspective, yielding exciting physical properties such as chiral charge carriers, the chiral anomaly, and weak anti-localization. It also shows promise for realizing topological electronic devices such as topological transistors. Herein, an overview of the substantial progress achieved in the last few years on Na3 Bi is presented, with a focus on technologically relevant large-area thin films synthesized via molecular beam epitaxy. Key theoretical aspects underpinning the unique electronic properties of Na3 Bi are introduced. Next, the growth process on different substrates is reviewed. Spectroscopic and microscopic features are illustrated, and an analysis of semiclassical and quantum transport phenomena in different doping regimes is provided. The emergent properties arising from confinement in two dimensions, including thickness-dependent and electric-field-driven topological phase transitions, are addressed, with an outlook toward current challenges and expected future progress.
Collapse
Affiliation(s)
- Iolanda Di Bernardo
- Australian Research Council Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, Victoria, 3800, Australia
- School of Physics and Astronomy, Monash University, Clayton, Victoria, 3800, Australia
| | - Jack Hellerstedt
- School of Physics and Astronomy, Monash University, Clayton, Victoria, 3800, Australia
| | - Chang Liu
- Australian Research Council Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, Victoria, 3800, Australia
- School of Physics and Astronomy, Monash University, Clayton, Victoria, 3800, Australia
| | - Golrokh Akhgar
- Australian Research Council Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, Victoria, 3800, Australia
- School of Physics and Astronomy, Monash University, Clayton, Victoria, 3800, Australia
| | - Weikang Wu
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore, 487372, Singapore
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore, 487372, Singapore
| | - Dimitrie Culcer
- Australian Research Council Centre of Excellence in Future Low-Energy Electronics Technologies, University of New South Wales, Sydney, New South Wales, 2052, Australia
- School of Physics, University of New South Wales, Sydney, New South Wales, 2052, Australia
| | - Sung-Kwan Mo
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Shaffique Adam
- Yale-NUS College, 16 College Ave West, Singapore, 138527, Singapore
| | - Mark T Edmonds
- Australian Research Council Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, Victoria, 3800, Australia
- School of Physics and Astronomy, Monash University, Clayton, Victoria, 3800, Australia
- Monash Centre for Atomically Thin Materials, Monash University, Clayton, Victoria, 3800, Australia
| | - Michael S Fuhrer
- Australian Research Council Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, Victoria, 3800, Australia
- School of Physics and Astronomy, Monash University, Clayton, Victoria, 3800, Australia
- Monash Centre for Atomically Thin Materials, Monash University, Clayton, Victoria, 3800, Australia
| |
Collapse
|
42
|
Zhao YX, Yang SA. Index Theorem on Chiral Landau Bands for Topological Fermions. Phys Rev Lett 2021; 126:046401. [PMID: 33576648 DOI: 10.1103/physrevlett.126.046401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 01/07/2021] [Indexed: 06/12/2023]
Abstract
Topological fermions as excitations from multidegenerate Fermi points have been attracting increasing interest in condensed matter physics. They are characterized by topological charges, and magnetic fields are usually applied in experiments for their detection. Here we present an index theorem that reveals the intrinsic connection between the topological charge of a Fermi point and the in-gap modes in the Landau band structure. The proof is based on mapping fermions under magnetic fields to a topological insulator whose topological number is exactly the topological charge of the Fermi point. Our Letter lays a solid foundation for the study of intriguing magnetoresponse effects of topological fermions.
Collapse
Affiliation(s)
- Y X Zhao
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| |
Collapse
|
43
|
Wang G, Li Z, Wu W, Guo H, Chen C, Yuan H, Yang SA. A two-dimensional h-BN/C 2N heterostructure as a promising metal-free photocatalyst for overall water-splitting. Phys Chem Chem Phys 2020; 22:24446-24454. [PMID: 33084701 DOI: 10.1039/d0cp03925j] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The construction of a heterostructure (HS) is an effective strategy to modulate the desired properties of two-dimensional (2D) materials and to extend their applications. In this paper, based on the density functional theory, we predict a metal-free type-II HS formed by h-BN and C2N single layers. The h-BN/C2N HS possesses a smaller bandgap than individual h-BN and C2N single layers, and it exhibits excellent visible light absorption. Importantly, its band edge positions satisfy the requirements for spontaneous water-splitting. With the assistance of the built-in electric field across the HS and the band offset, the photoinduced carriers can be readily spatially separated. Free energy calculations indicate the high catalytic activity for water oxidation and reduction reactions. The performance can be further enhanced by strain, which modulates the bandgap and the band edge positions of the HS. The band alignment may undergo a transition from type-I to type-II under strain, offering an effective switch for the reaction. The appropriate bandgap, suitable band edge positions, and effective carrier separation make the h-BN/C2N HS a promising candidate for use as a photocatalyst in water-splitting.
Collapse
Affiliation(s)
- Guangzhao Wang
- Key Laboratory of Micro Nano Optoelectronic Devices and Intelligent Perception Systems, Key Laboratory of Extraordinary Bond Engineering and Advanced Materials Technology of Chongqing, School of Electronic Information Engineering, Yangtze Normal University, Chongqing 408100, China.
| | | | | | | | | | | | | |
Collapse
|
44
|
Chen Y, Wu L, Xu H, Cong C, Li S, Feng S, Zhang H, Zou C, Shang J, Yang SA, Loh KP, Huang W, Yu T. Visualizing the Anomalous Charge Density Wave States in Graphene/NbSe 2 Heterostructures. Adv Mater 2020; 32:e2003746. [PMID: 33002238 DOI: 10.1002/adma.202003746] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 08/29/2020] [Indexed: 06/11/2023]
Abstract
Metallic layered transition metal dichalcogenides (TMDs) host collective many-body interactions, including the competing superconducting and charge density wave (CDW) states. Graphene is widely employed as a heteroepitaxial substrate for the growth of TMD layers and as an ohmic contact, where the graphene/TMD heterostructure is naturally formed. The presence of graphene can unpredictably influence the CDW order in 2D CDW conductors. This work reports the CDW transitions of 2H-NbSe2 layers in graphene/NbSe2 heterostructures. The evolution of Raman spectra demonstrates that the CDW phase transition temperatures (TCDW ) of NbSe2 are dramatically decreased when capped by graphene. The induced anomalous short-range CDW state is confirmed by scanning tunneling microscopy measurements. The findings propose a new criterion to determine the TCDW through monitoring the line shape of the A1g mode. Meanwhile, the 2D band is also discovered as an indicator to observe the CDW transitions. First-principles calculations imply that interfacial electron doping suppresses the CDW states by impeding the lattice distortion of 2H-NbSe2 . The extraordinary random CDW lattice suggests deep insight into the formation mechanism of many collective electronic states and possesses great potential in modulating multifunctional devices.
Collapse
Affiliation(s)
- Yu Chen
- Shaanxi Institute of Flexible Electronics (SIFE), Northwestern Polytechnical University (NPU), Xi'an, 710129, China
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
| | - Lishu Wu
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
| | - Hai Xu
- Department of Chemistry, National University of Singapore, Singapore, 117543, Singapore
- Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Science, Changchun, 130033, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100040, China
| | - Chunxiao Cong
- State Key Laboratory of ASIC and System, School of Information Science and Technology, Fudan University, Shanghai, 200433, China
- Academy for Engineering and Technology, Fudan University, Shanghai, 200433, China
| | - Si Li
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore, 487372, Singapore
| | - Shun Feng
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
| | - Hongbo Zhang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
| | - Chenji Zou
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
| | - Jingzhi Shang
- Shaanxi Institute of Flexible Electronics (SIFE), Northwestern Polytechnical University (NPU), Xi'an, 710129, China
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore, 487372, Singapore
| | - Kian Ping Loh
- Department of Chemistry, National University of Singapore, Singapore, 117543, Singapore
| | - Wei Huang
- Shaanxi Institute of Flexible Electronics (SIFE), Northwestern Polytechnical University (NPU), Xi'an, 710129, China
- Key Laboratory of Flexible Electronics (KLOFE) & Institute of Advanced Materials (IAM), Nanjing Tech University (NanjingTech), Nanjing, 211800, China
| | - Ting Yu
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
| |
Collapse
|
45
|
Yang Y, Gao Z, Feng X, Huang YX, Zhou P, Yang SA, Chong Y, Zhang B. Ideal Unconventional Weyl Point in a Chiral Photonic Metamaterial. Phys Rev Lett 2020; 125:143001. [PMID: 33064518 DOI: 10.1103/physrevlett.125.143001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 09/03/2020] [Indexed: 06/11/2023]
Abstract
Unconventional Weyl points (WPs), carrying topological charge 2 or higher, possess interesting properties different from ordinary charge-1 WPs, including multiple Fermi arcs that stretch over a large portion of the Brillouin zone. Thus far, such WPs have been observed in chiral materials and acoustic metamaterials, but there has been no clean demonstration in photonics in which the unconventional photonic WPs are separated from trivial bands. We experimentally realize an ideal symmetry-protected photonic charge-2 WP in a three-dimensional topological chiral microwave metamaterial. We use field mapping to directly observe the projected bulk dispersion, as well as the two long surface arcs that form a noncontractible loop wrapping around the surface Brillouin zone. The surface states span a record-wide frequency window of around 22.7% relative bandwidth. We demonstrate that the surface states exhibit a novel topological self-collimation property and are robust against disorder. This work provides an ideal photonic platform for exploring fundamental physics and applications of unconventional WPs.
Collapse
Affiliation(s)
- Yihao Yang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
- Centre for Disruptive Photonic Technologies, The Photonics Institute, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
| | - Zhen Gao
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
| | - Xiaolong Feng
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Yue-Xin Huang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Peiheng Zhou
- National Engineering Research Center of Electromagnetic Radiation Control Materials, State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Yidong Chong
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
- Centre for Disruptive Photonic Technologies, The Photonics Institute, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
| | - Baile Zhang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
- Centre for Disruptive Photonic Technologies, The Photonics Institute, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
| |
Collapse
|
46
|
Wang K, Dai JX, Shao LB, Yang SA, Zhao YX. Boundary Criticality of PT-Invariant Topology and Second-Order Nodal-Line Semimetals. Phys Rev Lett 2020; 125:126403. [PMID: 33016751 DOI: 10.1103/physrevlett.125.126403] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 08/06/2020] [Indexed: 06/11/2023]
Abstract
For conventional topological phases, the boundary gapless modes are determined by bulk topological invariants. Based on developing an analytic method to solve higher-order boundary modes, we present PT-invariant 2D topological insulators and 3D topological semimetals that go beyond this bulk-boundary correspondence framework. With unchanged bulk topological invariants, their first-order boundaries undergo transitions separating different phases with second-order boundary zero modes. For the 2D topological insulator, the helical edge modes appear at the transition point for two second-order topological insulator phases with diagonal and off-diagonal corner zero modes, respectively. Accordingly, for the 3D topological semimetal, the criticality corresponds to surface helical Fermi arcs of a Dirac semimetal phase. Interestingly, we find that the 3D system generically belongs to a novel second-order nodal-line semimetal phase, possessing gapped surfaces but a pair of diagonal or off-diagonal hinge Fermi arcs.
Collapse
Affiliation(s)
- Kai Wang
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - Jia-Xiao Dai
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - L B Shao
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Y X Zhao
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| |
Collapse
|
47
|
Zhang W, Wang S, Yang SA, Xia XH, Zhou YG. Plasmon of Au nanorods activates metal-organic frameworks for both the hydrogen evolution reaction and oxygen evolution reaction. Nanoscale 2020; 12:17290-17297. [PMID: 32789321 DOI: 10.1039/d0nr04562d] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Electrocatalytic water splitting holds great promise for renewable energy conversion and storage systems. However, it usually suffers from sluggish kinetics, which greatly hinders its real application. Here, we demonstrate the utilization of the localized surface plasmon resonance (LSPR) of Au nanorods (AuNRs) to significantly improve the electroactivity of both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) at Co-MOF nanosheets (Co-MOFNs) under different polarizations. Theoretical calculations suggest that the HER enhancement can be largely attributed to the injection of hot electrons from plasmonic AuNRs to Co-MOFN catalysts, which upraises the Fermi level of Co-MOFNs, increasing their reductive activity towards the HER. Regarding the promotion of the OER, it is indicated that the formed holes in Co-MOFNs should majorly locate on the surface oxygen atoms, which may also serve as active positions working jointly with neighboring Co atoms in oxidizing OH-. The plasmon enhanced HER and OER electrocatalysis could also be observed over AuNR/Ni-MOFN and AuNR/NiCo-MOFN catalysts, suggesting the generality of this strategy. This study highlights the possibility of accelerating both the HER and OER efficiency by AuNR plasmonic excitation and provides a new route towards the design of more efficient water splitting systems with the assistance of light energy.
Collapse
Affiliation(s)
- Wenmin Zhang
- Institute of Chemical Biology and Nanomedicine (ICBN), State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, P. R. China.
| | - Shanshan Wang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore, 487372, Singapore and School of Physics, Southeast University, Nanjing, 211189, China
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore, 487372, Singapore
| | - Xing-Hua Xia
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, China
| | - Yi-Ge Zhou
- Institute of Chemical Biology and Nanomedicine (ICBN), State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, P. R. China.
| |
Collapse
|
48
|
Wang X, Xiao C, Yang C, Chen M, Yang SA, Hu J, Ren Z, Pan H, Zhu W, Xu ZA, Lu Y. Ferroelectric control of single-molecule magnetism in 2D limit. Sci Bull (Beijing) 2020; 65:1252-1259. [PMID: 36747412 DOI: 10.1016/j.scib.2020.04.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 03/10/2020] [Accepted: 03/30/2020] [Indexed: 11/17/2022]
Abstract
The electric control of magnetic properties based on magnetoelectric effect is crucial for the development of future data storage devices. Here, based on first-principles calculations, a strong magnetoelectric effect is proposed to effectively switch on/off the magnetic states as well as alter the in-plane/perpendicular easy axes of metal-phthalocyanine molecules (MPc) by reversing the electric polarization of the underlying two-dimensional (2D) ferroelectric α-In2Se3 substrate with the application of an external electric field. The mechanism originates from the different hybridization between the molecule and the ferroelectric substrate in which the different electronic states of surface Se layer play a dominant role. Moreover, the magnetic moments and magnetic anisotropy energies (MAE) of OsPc/In2Se3 can be further largely enhanced by a functionalized atom atop the OsPc molecule. The I-OsPc/In2Se3 system possesses large MAE up to 30 meV at both polarization directions, which is sufficient for room-temperature applications. These findings provide a feasible scheme to realize ferroelectric control of magnetic states in 2D limit, which have great potential for applications in nanoscale electronics and spintronics.
Collapse
Affiliation(s)
- Xinwei Wang
- State Key Laboratory of Silicon Materials and School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Chengcheng Xiao
- State Key Laboratory of Silicon Materials and School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China; Departments of Materials and the Thomas Young Centre for Theory and Simulation of Materials, Imperial College London, London SW7 2AZ, UK
| | - Chao Yang
- State Key Laboratory of Silicon Materials and School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Miaogen Chen
- Department of Physics, China Jiliang University, Hangzhou 310018, China
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Jun Hu
- School of Physical Science and Technology, Soochow University, Suzhou 215006, China.
| | - Zhaohui Ren
- State Key Laboratory of Silicon Materials and School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Hui Pan
- Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Macao SAR, China
| | - Wenguang Zhu
- ICQD, Hefei National Laboratory for Physical Science at the Microscale, Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences, Department of Physics, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China.
| | - Zhu-An Xu
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou 310027, China; Collaborative Innovation Centre of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Yunhao Lu
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou 310027, China.
| |
Collapse
|
49
|
Liu Y, Yu ZM, Xiao C, Yang SA. Quantized Circulation of Anomalous Shift in Interface Reflection. Phys Rev Lett 2020; 125:076801. [PMID: 32857537 DOI: 10.1103/physrevlett.125.076801] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 07/07/2020] [Accepted: 07/27/2020] [Indexed: 06/11/2023]
Abstract
A particle beam may undergo an anomalous spatial shift when it is reflected at an interface. The shift forms a vector field defined in the two-dimensional interface momentum space. We show that, although the shift vector at individual momentum is typically sensitive to the system details, its integral along a close loop, i.e., its circulation, could yield a robust quantized number under certain conditions of interest. Particularly, this is the case when the beam is incident from a trivial medium, then the quantized circulation of anomalous shift (CAS) directly manifests the topological character of the other medium. We demonstrate that the topological charge of a Weyl medium as well as the unconventional pair potentials of a superconductor can be captured and distinguished by CAS. Our work unveils a hidden quantized feature in a ubiquitous physical process, which may also offer a new approach for probing topological media.
Collapse
Affiliation(s)
- Ying Liu
- School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Zhi-Ming Yu
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
- Key Lab of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), Beijing Key Lab of Nanophotonics & Ultrafine Optoelectronic Systems, and School of Physics, Beijing Institute of Technology, Beijing 100081, China
| | - Cong Xiao
- Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
- Center for Quantum Transport and Thermal Energy Science, School of Physics and Technology, Nanjing Normal University, Nanjing 210023, China
| |
Collapse
|
50
|
Chen C, Song Z, Zhao JZ, Chen Z, Yu ZM, Sheng XL, Yang SA. Universal Approach to Magnetic Second-Order Topological Insulator. Phys Rev Lett 2020; 125:056402. [PMID: 32794859 DOI: 10.1103/physrevlett.125.056402] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 07/06/2020] [Indexed: 06/11/2023]
Abstract
We propose a universal practical approach to realize magnetic second-order topological insulator (SOTI) materials, based on properly breaking the time reversal symmetry in conventional (first-order) topological insulators. The approach works for both three dimensions (3D) and two dimensions (2D), and is particularly suitable for 2D, where it can be achieved by coupling a quantum spin Hall insulator with a magnetic substrate. Using first-principles calculations, we predict bismuthene on EuO(111) surface as the first realistic system for a two-dimensional magnetic SOTI. We explicitly demonstrate the existence of the protected corner states. Benefitting from the large spin-orbit coupling and sizable magnetic proximity effect, these corner states are located in a boundary gap ∼83 meV, and hence can be readily probed in experiment. By controlling the magnetic phase transition, a topological phase transition between a first-order TI and a SOTI can be simultaneously achieved in the system. The effect of symmetry breaking, the connection with filling anomaly, and the experimental detection are discussed.
Collapse
Affiliation(s)
- Cong Chen
- Key Laboratory of Micro-nano Measurement-Manipulation and Physics (Ministry of Education), School of Physics, Beihang University, Beijing 100191, China
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Zhida Song
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Jian-Zhou Zhao
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
- Sichuan Co-Innovation Center for New Energetic Materials, Southwest University of Science and Technology, Mianyang 621010, China
| | - Ziyu Chen
- Key Laboratory of Micro-nano Measurement-Manipulation and Physics (Ministry of Education), School of Physics, Beihang University, Beijing 100191, China
| | - Zhi-Ming Yu
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
- Key Lab of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems, and School of Physics, Beijing Institute of Technology, Beijing 100081, China
| | - Xian-Lei Sheng
- Key Laboratory of Micro-nano Measurement-Manipulation and Physics (Ministry of Education), School of Physics, Beihang University, Beijing 100191, China
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
- Center for Quantum Transport and Thermal Energy Science, School of Physics and Technology, Nanjing Normal University, Nanjing 210023, China
| |
Collapse
|