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Tang J, Cheng R. Lossless Spin-Orbit Torque in Antiferromagnetic Topological Insulator MnBi_{2}Te_{4}. PHYSICAL REVIEW LETTERS 2024; 132:136701. [PMID: 38613287 DOI: 10.1103/physrevlett.132.136701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Revised: 08/22/2023] [Accepted: 02/23/2024] [Indexed: 04/14/2024]
Abstract
We formulate and quantify the spin-orbit torque (SOT) in intrinsic antiferromagnetic topological insulator MnBi_{2}Te_{4} of a few septuple-layer thick in charge-neutral condition, which exhibits pronounced layer-resolved characteristics and even-odd contrast. Contrary to traditional current-induced torques, our SOT is not accompanied by Ohm's currents, thus being devoid of Joule heating. We study the SOT-induced magnetic resonances, where in the tri-septuple-layer case we identify a peculiar exchange mode that is blind to microwaves but can be exclusively driven by the predicted SOT. As an inverse effect, the dynamical magnetic moments generate a pure adiabatic current, which occurs concomitantly with the SOT and gives rise to an overall reactance for the MnBi_{2}Te_{4}, enabling a lossless conversion of electric power into magnetic dynamics.
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Affiliation(s)
- Junyu Tang
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - Ran Cheng
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
- Department of Electrical and Computer Engineering, University of California, Riverside, California 92521, USA
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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. PHYSICAL REVIEW LETTERS 2023; 130:166302. [PMID: 37154629 DOI: 10.1103/physrevlett.130.166302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [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.
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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
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