1
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Wang J, Nikonov DE, Lin H, Kang D, Kim R, Li H, Klimeck G. First-Principles Simulation and Materials Screening for Spin-Orbit Torque in 2D van der Waals Heterostructures. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2308965. [PMID: 38693077 DOI: 10.1002/smll.202308965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Revised: 02/05/2024] [Indexed: 05/03/2024]
Abstract
Recent advancements in spin-orbit torque (SOT) technology in two-dimensional van der Waals (2D vdW) materials have not only pushed spintronic devices to their atomic limits but have also unveiled unconventional torques and novel spin-switching mechanisms. The vast diversity of SOT observed in numerous 2D vdW materials necessitates a screening strategy to identify optimal materials for torque device performance. However, such a strategy has yet to be established. To address this critical issue, a combination of density functional theory and non-equilibrium Green's function is employed to calculate the SOT in various 2D vdW bilayer heterostructures. This leads to the discovery of three high SOT systems: WTe2/CrSe2, MoTe2/VS2, and NbSe2/CrSe2. Furthermore, a figure of merit that allows for rapid and efficient estimation of SOT is proposed, enabling high-throughput screening of optimal materials and devices for SOT applications in the future.
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Affiliation(s)
- Jinying Wang
- Network for Computational Nanotechnology, Purdue University, West Lafayette, IN, 47907, USA
| | | | - Hongyang Lin
- School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN, 47907, USA
| | - Dain Kang
- School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN, 47907, USA
| | - Raseong Kim
- Components Research, Intel, Hillsboro, OR, 97124, USA
| | - Hai Li
- Components Research, Intel, Hillsboro, OR, 97124, USA
| | - Gerhard Klimeck
- Network for Computational Nanotechnology, Purdue University, West Lafayette, IN, 47907, USA
- School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN, 47907, USA
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2
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Wang F, Shi G, Yang D, Tan HR, Zhang C, Lei J, Pu Y, Yang S, Soumyanarayanan A, Elyasi M, Yang H. Deterministic switching of perpendicular magnetization by out-of-plane anti-damping magnon torques. NATURE NANOTECHNOLOGY 2024:10.1038/s41565-024-01741-y. [PMID: 39048707 DOI: 10.1038/s41565-024-01741-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Accepted: 06/12/2024] [Indexed: 07/27/2024]
Abstract
Spin-wave excitations of magnetic moments (or magnons) can transport spin angular momentum in insulating magnetic materials. This property distinguishes magnonic devices from traditional electronics, where power consumption results from electrons' movement. Recently, magnon torques have been used to switch perpendicular magnetization in the presence of an external magnetic field. Here we present a material system composed of WTe2/antiferromagnetic insulator NiO/ferromagnet CoFeB heterostructures that allows magnetic field-free switching of the perpendicular magnetization. The magnon currents, with a spin polarization canting of -8.5° relative to the sample plane, traverse the 25-nm-thick polycrystalline NiO layer while preserving their original polarization direction, subsequently exerting an out-of-plane anti-damping magnon torque on the ferromagnetic layer. Using this mechanism, we achieve a 190-fold reduction in power consumption in PtTe2/WTe2/NiO/CoFeB heterostructures compared to Bi2Te3/NiO/CoFeB control samples, which only exhibit in-plane magnon torques. Our field-free demonstration contributes to the realization of all-electric, low-power, perpendicular magnetization switching devices.
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Affiliation(s)
- Fei Wang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
- Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education and School of Chemistry and Materials Science, Shanxi Normal University, Taiyuan, China
| | - Guoyi Shi
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Dongsheng Yang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Hui Ru Tan
- Institute of Materials Research and Engineering, Agency for Science, Technology & Research (A*STAR), Singapore, Singapore
| | - Chenhui Zhang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Jiayu Lei
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Yuchen Pu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Shuhan Yang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Anjan Soumyanarayanan
- Institute of Materials Research and Engineering, Agency for Science, Technology & Research (A*STAR), Singapore, Singapore
- Department of Physics, National University of Singapore, Singapore, Singapore
| | - Mehrdad Elyasi
- Advanced Institute for Materials Research, Tohoku University, Sendai, Japan.
| | - Hyunsoo Yang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore.
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3
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Abdelwahab I, Kumar D, Bian T, Zheng H, Gao H, Hu F, McClelland A, Leng K, Wilson WL, Yin J, Yang H, Loh KP. Two-dimensional chiral perovskites with large spin Hall angle and collinear spin Hall conductivity. Science 2024; 385:311-317. [PMID: 39024425 DOI: 10.1126/science.adq0967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Accepted: 06/10/2024] [Indexed: 07/20/2024]
Abstract
Two-dimensional hybrid organic-inorganic perovskites with chiral spin texture are emergent spin-optoelectronic materials. Despite the wealth of chiro-optical studies on these materials, their charge-to-spin conversion efficiency is unknown. We demonstrate highly efficient electrically driven charge-to-spin conversion in enantiopure chiral perovskites (R/S-MB)2(MA)3Pb4I13 (〈n〉 = 4), where MB is 2-methylbutylamine, MA is methylamine, Pb is lead, and I is iodine. Using scanning photovoltage microscopy, we measured a spin Hall angle θsh of 5% and a spin lifetime of ~75 picoseconds at room temperature in 〈n〉 = 4 chiral perovskites, which is much larger than its racemic counterpart as well as the lower 〈n〉 homologs. In addition to current-induced transverse spin current, the presence of a coexisting out-of-plane spin current confirms that both conventional and collinear spin Hall conductivities exist in these low-dimensional crystals.
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Affiliation(s)
- Ibrahim Abdelwahab
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
- Center for Nanoscale Systems, Harvard University, Cambridge, MA 02138, USA
| | - Dushyant Kumar
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
- Department of Physics, Netaji Subhas University of Technology (NSUT), Dwarka, New Delhi 110078, India
| | - Tieyuan Bian
- Department of Applied Physics, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR
| | - Haining Zheng
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
| | - Heng Gao
- Department of Physics, Shanghai University, Shanghai 200444, China
| | - Fanrui Hu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
| | - Arthur McClelland
- Center for Nanoscale Systems, Harvard University, Cambridge, MA 02138, USA
| | - Kai Leng
- Department of Applied Physics, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR
| | - William L Wilson
- Center for Nanoscale Systems, Harvard University, Cambridge, MA 02138, USA
| | - Jun Yin
- Department of Applied Physics, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR
| | - Hyunsoo Yang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
| | - Kian Ping Loh
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
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4
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Chen H, Tian W, Zhang L, Song P, Jia L, Chen J, Zhu Z, Feng YP, Loh KP. Highly Efficient Spin Injection and Readout Across Van Der Waals Interface. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024:e2403073. [PMID: 38966892 DOI: 10.1002/smll.202403073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Revised: 06/25/2024] [Indexed: 07/06/2024]
Abstract
Spin injection, transport, and detection across the interface between a ferromagnet and a spin-carrying channel are crucial for energy-efficient spin logic devices. However, interfacial conductance mismatch, spin dephasing, and inefficient spin-to-charge conversion significantly reduce the efficiency of these processes. In this study, it is demonstrated that an all van der Waals heterostructure consisting of a ferromagnet (Fe3GeTe2) and Weyl semimetal enables a large spin readout efficiency. Specifically, a nonlocal spin readout signal of 150 mΩ and a local spin readout signal of 7.8 Ω is achieved, which reach the signal level useful for practical spintronic devices. The remarkable spin readout signal is attributed to suppressed spin dephasing channels at the vdW interfaces, long spin diffusion, and efficient charge-spin interconversion in Td-MoTe2. These findings highlight the potential of vdW heterostructures for spin Hall effect-enabled spin detection with high efficiency, opening up new possibilities for spin-orbit logic devices using vdW interfaces.
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Affiliation(s)
- Hao Chen
- Department of Chemistry, National University of Singapore, Singapore, 117543, Singapore
| | - Wanghao Tian
- School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Lishu Zhang
- Department of Physics, National University of Singapore, Singapore, 117551, Singapore
| | - Peng Song
- School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 639798, Singapore
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
- CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, Singapore, 637553, Singapore
| | - Lanxin Jia
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Jingsheng Chen
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Zhifeng Zhu
- School of Information Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Yuan Ping Feng
- Department of Physics, National University of Singapore, Singapore, 117551, Singapore
| | - Kian Ping Loh
- Department of Chemistry, National University of Singapore, Singapore, 117543, Singapore
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5
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Liang X, Lv P, Xiong Y, Chen X, Fu D, Feng Y, Wang X, Chen X, Xu G, Kan E, Xu F, Zeng H. Moiré Engineering of Spin-Orbit Torque by Twisted WS 2 Homobilayers. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2313059. [PMID: 38871341 DOI: 10.1002/adma.202313059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2023] [Revised: 05/28/2024] [Indexed: 06/15/2024]
Abstract
Artificial moiré superlattices created by stacking 2D crystals have emerged as a powerful platform with unprecedented material-engineering capabilities. While moiré superlattices are reported to host a number of novel quantum states, their potential for spintronic applications remains largely unexplored. Here, the effective manipulation of spin-orbit torque (SOT) is demonstrated using moiré superlattices in ferromagnetic devices comprised of twisted WS2/WS2 homobilayer (t-WS2) and CoFe/Pt thin films by altering twisting angle (θ) and gate voltage. Notably, a substantial enhancement of up to 44.5% is observed in SOT conductivity at θ ≈ 8.3°. Furthermore, compared to the WS2 monolayer and untwisted WS2/WS2 bilayers, the moiré superlattices in t-WS2 enable a greater gate-voltage tunability of SOT conductivity. These results are related to the generation of the interfacial moiré magnetic field by the real-space Berry phase in moiré superlattices, which modulates the absorption of the spin-Hall current arising from Pt through the magnetic proximity effect. This study highlights the moiré physics as a new building block for designing enhanced spintronic devices.
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Affiliation(s)
- Xiaorong Liang
- MIIT Key Laboratory of Advanced Display Materials and Devices, Institute of Optoelectronics and Nanomaterials, College of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China
| | - Penghao Lv
- MIIT Key Laboratory of Advanced Display Materials and Devices, Institute of Optoelectronics and Nanomaterials, College of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China
| | - Yunhai Xiong
- MIIT Key Laboratory of Advanced Display Materials and Devices, Institute of Optoelectronics and Nanomaterials, College of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China
| | - Xi Chen
- MIIT Key Laboratory of Advanced Display Materials and Devices, Institute of Optoelectronics and Nanomaterials, College of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China
| | - Di Fu
- MIIT Key Laboratory of Advanced Display Materials and Devices, Institute of Optoelectronics and Nanomaterials, College of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China
| | - Yiping Feng
- MIIT Key Laboratory of Advanced Display Materials and Devices, Institute of Optoelectronics and Nanomaterials, College of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China
| | - Xusheng Wang
- MIIT Key Laboratory of Advanced Display Materials and Devices, Institute of Optoelectronics and Nanomaterials, College of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China
| | - Xiang Chen
- MIIT Key Laboratory of Advanced Display Materials and Devices, Institute of Optoelectronics and Nanomaterials, College of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China
| | - Guizhou Xu
- MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology, College of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China
| | - Erjun Kan
- MIIT Key Laboratory of Semiconductor Microstructure and Quantum Sensing, School of Physics, Nanjing University of Science and Technology, Nanjing, 210094, China
| | - Feng Xu
- MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology, College of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China
| | - Haibo Zeng
- MIIT Key Laboratory of Advanced Display Materials and Devices, Institute of Optoelectronics and Nanomaterials, College of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China
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6
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Shi G, Wang F, Liu Y, Li Z, Tan HR, Yang D, Soumyanarayanan A, Yang H. Field-Free Manipulation of Two-Dimensional Ferromagnet CrTe 2 by Spin-Orbit Torques. NANO LETTERS 2024. [PMID: 38856112 DOI: 10.1021/acs.nanolett.4c01366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
Electrical manipulation of magnetic states in two-dimensional ferromagnetic systems is crucial in information storage and low-dimensional spintronics. Spin-orbit torque presents a rapid and energy-efficient method for electrical control of the magnetization. In this letter, we demonstrate a wafer-scale spin-orbit torque switching of two-dimensional ferromagnetic states. Using molecular beam epitaxy, we fabricate two-dimensional heterostructures composed of low crystal-symmetry WTe2 and ferromagnet CrTe2 with perpendicular anisotropy. By utilizing out-of-plane spins generated from WTe2, we achieve field-free switching of the CrTe2 perpendicular magnetization. The threshold switching current density in CrTe2/WTe2 is 1.2 × 106 A/cm2, 20 times smaller than that of the CrTe2/Pt control sample even with an external magnetic field. In addition, the switching behavior can be modulated by external magnetic fields and crystal symmetry. Our findings demonstrate a controllable and all-electric manipulation of perpendicular magnetization in a two-dimensional ferromagnet, representing a significant advancement toward the practical implementation of low-dimensional spintronic devices.
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Affiliation(s)
- Guoyi Shi
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
| | - Fei Wang
- Key Laboratory of Magnetic Molecules and Magnetic Information, Materials of Ministry of Education, School of Chemistry and Materials Science, Shanxi Normal University, Taiyuan 030006, China
| | - Yakun Liu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
| | - Zhaohui Li
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
| | - Hui Ru Tan
- Institute of Materials Research & Engineering, Agency for Science, Technology & Research (A*STAR), Singapore 138634, Singapore
| | - Dongsheng Yang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
| | - Anjan Soumyanarayanan
- Institute of Materials Research & Engineering, Agency for Science, Technology & Research (A*STAR), Singapore 138634, Singapore
- Department of Physics, National University of Singapore, Singapore 117551, Singapore
| | - Hyunsoo Yang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
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7
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Wang F, Shi G, Kim KW, Park HJ, Jang JG, Tan HR, Lin M, Liu Y, Kim T, Yang D, Zhao S, Lee K, Yang S, Soumyanarayanan A, Lee KJ, Yang H. Field-free switching of perpendicular magnetization by two-dimensional PtTe 2/WTe 2 van der Waals heterostructures with high spin Hall conductivity. NATURE MATERIALS 2024; 23:768-774. [PMID: 38243113 DOI: 10.1038/s41563-023-01774-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 11/28/2023] [Indexed: 01/21/2024]
Abstract
The key challenge of spin-orbit torque applications lies in exploring an excellent spin source capable of generating out-of-plane spins while exhibiting high spin Hall conductivity. Here we combine PtTe2 for high spin conductivity and WTe2 for low crystal symmetry to satisfy the above requirements. The PtTe2/WTe2 bilayers exhibit a high in-plane spin Hall conductivity σs,y ≈ 2.32 × 105 × ħ/2e Ω-1 m-1 and out-of-plane spin Hall conductivity σs,z ≈ 0.25 × 105 × ħ/2e Ω-1 m-1, where ħ is the reduced Planck's constant and e is the value of the elementary charge. The out-of-plane spins in PtTe2/WTe2 bilayers enable the deterministic switching of perpendicular magnetization at room temperature without magnetic fields, and the power consumption is 67 times smaller than that of the Pt control case. The high out-of-plane spin Hall conductivity is attributed to the conversion from in-plane spin to out-of-plane spin, induced by the crystal asymmetry of WTe2. Our work establishes a low-power perpendicular magnetization manipulation based on wafer-scale two-dimensional van der Waals heterostructures.
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Affiliation(s)
- Fei Wang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Guoyi Shi
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
- Integrative Sciences and Engineering Programme, NUS Graduate School, National University of Singapore, Singapore, Singapore
| | - Kyoung-Whan Kim
- Center of Spintronics, Korea Institute of Science and Technology, Seoul, Korea
| | - Hyeon-Jong Park
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Korea
| | - Jae Gwang Jang
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea
| | - Hui Ru Tan
- Institute of Materials Research & Engineering, Agency for Science Technology & Research (A*STAR), Singapore, Singapore
| | - Ming Lin
- Institute of Materials Research & Engineering, Agency for Science Technology & Research (A*STAR), Singapore, Singapore
| | - Yakun Liu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Taeheon Kim
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Dongsheng Yang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Shishun Zhao
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Kyusup Lee
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Shuhan Yang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Anjan Soumyanarayanan
- Institute of Materials Research & Engineering, Agency for Science Technology & Research (A*STAR), Singapore, Singapore
- Department of Physics, National University of Singapore, Singapore, Singapore
| | - Kyung-Jin Lee
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea.
| | - Hyunsoo Yang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore.
- Integrative Sciences and Engineering Programme, NUS Graduate School, National University of Singapore, Singapore, Singapore.
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8
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Bainsla L, Zhao B, Behera N, Hoque AM, Sjöström L, Martinelli A, Abdel-Hafiez M, Åkerman J, Dash SP. Large out-of-plane spin-orbit torque in topological Weyl semimetal TaIrTe 4. Nat Commun 2024; 15:4649. [PMID: 38821948 PMCID: PMC11143358 DOI: 10.1038/s41467-024-48872-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2023] [Accepted: 05/16/2024] [Indexed: 06/02/2024] Open
Abstract
The unique electronic properties of topological quantum materials, such as protected surface states and exotic quasiparticles, can provide an out-of-plane spin-polarized current needed for external field-free magnetization switching of magnets with perpendicular magnetic anisotropy. Conventional spin-orbit torque (SOT) materials provide only an in-plane spin-polarized current, and recently explored materials with lower crystal symmetries provide very low out-of-plane spin-polarized current components, which are not suitable for energy-efficient SOT applications. Here, we demonstrate a large out-of-plane damping-like SOT at room temperature using the topological Weyl semimetal candidate TaIrTe4 with a lower crystal symmetry. We performed spin-torque ferromagnetic resonance (STFMR) and second harmonic Hall measurements on devices based on TaIrTe4/Ni80Fe20 heterostructures and observed a large out-of-plane damping-like SOT efficiency. The out-of-plane spin Hall conductivity is estimated to be (4.05 ± 0.23)×104 (ℏ ⁄ 2e) (Ωm)-1, which is an order of magnitude higher than the reported values in other materials.
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Affiliation(s)
- Lakhan Bainsla
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, SE-41296, Göteborg, Sweden.
- Department of Physics, Indian Institute of Technology Ropar, Rupnagar, 140001, Punjab, India.
| | - Bing Zhao
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, SE-41296, Göteborg, Sweden
| | - Nilamani Behera
- Department of Physics, University of Gothenburg, Göteborg, SE-41296, Göteborg, Sweden
| | - Anamul Md Hoque
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, SE-41296, Göteborg, Sweden
| | - Lars Sjöström
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, SE-41296, Göteborg, Sweden
| | - Anna Martinelli
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Göteborg, 41296, Sweden
| | - Mahmoud Abdel-Hafiez
- Department of Applied Physics and Astronomy, University of Sharjah, P. O. Box 27272, Sharjah, United Arab Emirates
- Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20, Uppsala, Sweden
| | - Johan Åkerman
- Department of Physics, University of Gothenburg, Göteborg, SE-41296, Göteborg, Sweden
- Center for Science and Innovation in Spintronics, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
- Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
| | - Saroj P Dash
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, SE-41296, Göteborg, Sweden.
- Wallenberg Initiative Materials Science for Sustainability, Department of Microtechnology and Nanoscience, Chalmers University of Technology, SE-41296, Göteborg, Sweden.
- Graphene Center, Chalmers University of Technology, SE-41296, Göteborg, Sweden.
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9
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Farokhnezhad M, Cullen JH, Culcer D. Spin-orbit torques due to topological insulator surface states: an in-plane magnetization as a probe of extrinsic spin-orbit scattering. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:315004. [PMID: 38663418 DOI: 10.1088/1361-648x/ad43a6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Accepted: 04/25/2024] [Indexed: 05/09/2024]
Abstract
Topological insulator (TI) surface states exert strong spin-orbit torques. When the magnetization is in the plane its interaction with the TI conduction electrons is non-trivial, and is influenced by extrinsic spin-orbit scattering. This is expected to be strong in TIs but is difficult to calculate and to measure unambiguously. Here we show that extrinsic spin-orbit scattering sizably renormalizes the surface state spin-orbit torque resulting in a strong density dependence. The magnitude of the renormalization of the spin torque and the effect of spin-orbit scattering on the relative sizes of the in-plane and out-of-plane field-like torques have strong implications for experiment: We propose two separate experimental signatures for the measurement of its presence.
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Affiliation(s)
- Mohsen Farokhnezhad
- Department of Physics, School of Science, Shiraz University, Shiraz 71946-84795, Iran
- School of Nanoscience, Institute for Research in Fundamental Sciences, IPM, Tehran 19395-5531, Iran
- School of Physics, Institute for Research in Fundamental Sciences, IPM, Tehran 19395-5531, Iran
| | - James H Cullen
- School of Physics, University of New South Wales, Kensington, NSW 2052, Australia
| | - Dimitrie Culcer
- School of Physics, University of New South Wales, Kensington, NSW 2052, Australia
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10
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Cao L, Chen Q, Zhu Y, Tong K, Li W, Ma J, Jalali M, Huang Z, Wu J, Zhai Y. Interfacial Modulation of Spin-Orbit Torques Induced by Two-Dimensional van der Waals Material ZrSe 3. ACS APPLIED MATERIALS & INTERFACES 2024; 16:19764-19770. [PMID: 38577833 DOI: 10.1021/acsami.4c00881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/06/2024]
Abstract
Two-dimensional van der Waals (2D vdW) materials are widely used in spin-orbit torque (SOT) devices. Recent studies have demonstrated the low crystal symmetry and large spin Hall conductivity of 2D vdW ZrSe3, indicating its potential applications in low-power SOT devices. Here, we study the interfacial contribution of SOTs and current-induced magnetization switching in the ZrSe3/Py (Ni80Fe20) and ZrSe3/Cu/Py heterostructures. SOT efficiencies of samples are detected by the spin-torque ferromagnetic resonance (ST-FMR), and out-of-plane damping-like torque (τB) is observed. The ratio between τB and the field-like torque (τA) decreases from 0.175 to 0.138 when inserting 1 nm Cu at the interface and then drops to 0.001 when the thickness of Cu intercalation is 2 nm, indicating that Cu intercalation inhibits the τB component of SOT. Moreover, the SOT efficiency is increased from 3.05 to 5.21, which may be attributed to the Cu intercalation being beneficial to improve the interface between Py and ZrSe3. Theoretical calculation has shown that the Cu spacer can change the conductivity of ZrSe3 from semiconductor to conductor, thereby decreasing the Schottky barrier and increasing the transmission efficiency of the spin current. Furthermore, magneto-optical Kerr effect (MOKE) microscopy is employed to verify the current-driven magnetization switching in these structures. In comparison to the ZrSe3/Py bilayer, the critical current density of ZrSe3/Cu/Py is reduced when inserting 1 nm Cu, demonstrating the higher SOT efficiency and lower power consumption in ZrSe3/Cu/Py structures.
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Affiliation(s)
- Lulu Cao
- Key Laboratory of Quantum Materials and Devices of Ministry of Education, School of Physics, Southeast University, Nanjing, Jiangsu 211189, People's Republic of China
| | - Qian Chen
- Key Laboratory of Quantum Materials and Devices of Ministry of Education, School of Physics, Southeast University, Nanjing, Jiangsu 211189, People's Republic of China
| | - Yonghui Zhu
- Key Laboratory of Quantum Materials and Devices of Ministry of Education, School of Physics, Southeast University, Nanjing, Jiangsu 211189, People's Republic of China
| | - Kaiyu Tong
- Department of Physics, Engineering and Technology, University of York, York YO10 5DD, United Kingdom
| | - Wenjia Li
- Department of Physics, Engineering and Technology, University of York, York YO10 5DD, United Kingdom
| | - Jun Ma
- Department of Physics, Engineering and Technology, University of York, York YO10 5DD, United Kingdom
| | - Milad Jalali
- Key Laboratory of Quantum Materials and Devices of Ministry of Education, School of Physics, Southeast University, Nanjing, Jiangsu 211189, People's Republic of China
| | - Zhaocong Huang
- Key Laboratory of Quantum Materials and Devices of Ministry of Education, School of Physics, Southeast University, Nanjing, Jiangsu 211189, People's Republic of China
| | - Jing Wu
- Department of Physics, Engineering and Technology, University of York, York YO10 5DD, United Kingdom
| | - Ya Zhai
- Key Laboratory of Quantum Materials and Devices of Ministry of Education, School of Physics, Southeast University, Nanjing, Jiangsu 211189, People's Republic of China
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11
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Zhang H, Chen X, Wang T, Huang X, Chen X, Shao YT, Meng F, Meisenheimer P, N'Diaye A, Klewe C, Shafer P, Pan H, Jia Y, Crommie MF, Martin LW, Yao J, Qiu Z, Muller DA, Birgeneau RJ, Ramesh R. Room-Temperature, Current-Induced Magnetization Self-Switching in A Van Der Waals Ferromagnet. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2308555. [PMID: 38016700 DOI: 10.1002/adma.202308555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 10/30/2023] [Indexed: 11/30/2023]
Abstract
2D layered materials with broken inversion symmetry are being extensively pursued as spin source layers to realize high-efficiency magnetic switching. Such low-symmetry layered systems are, however, scarce. In addition, most layered magnets with perpendicular magnetic anisotropy show a low Curie temperature. Here, the experimental observation of spin-orbit torque magnetization self-switching at room temperature in a layered polar ferromagnetic metal, Fe2.5 Co2.5 GeTe2 is reported. The spin-orbit torque is generated from the broken inversion symmetry along the c-axis of the crystal. These results provide a direct pathway toward applicable 2D spintronic devices.
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Affiliation(s)
- Hongrui Zhang
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Xiang Chen
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Physics, University of California, Berkeley, CA, 94720, USA
| | - Tianye Wang
- Department of Physics, University of California, Berkeley, CA, 94720, USA
| | - Xiaoxi Huang
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
| | - Xianzhe Chen
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Yu-Tsun Shao
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, 14853, USA
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA, 90089, USA
| | - Fanhao Meng
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Peter Meisenheimer
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
| | - Alpha N'Diaye
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Christoph Klewe
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Padraic Shafer
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Hao Pan
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
| | - Yanli Jia
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
| | - Michael F Crommie
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Physics, University of California, Berkeley, CA, 94720, USA
| | - Lane W Martin
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Departments of Materials Science and NanoEngineering, Chemistry, and Physics and Astronomy, Rice University, Houston, TX, 77005, USA
- Rice Advanced Materials Institute, Rice University, Houston, TX, 77005, USA
| | - Jie Yao
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Ziqiang Qiu
- Department of Physics, University of California, Berkeley, CA, 94720, USA
| | - David A Muller
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, 14853, USA
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, 14853, USA
| | - Robert J Birgeneau
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Physics, University of California, Berkeley, CA, 94720, USA
| | - Ramamoorthy Ramesh
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Physics, University of California, Berkeley, CA, 94720, USA
- Department of Physics and Astronomy, Department of Materials Science and Nanoengineering, Rice University, Houston, TX, 77005, USA
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12
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Cheng E, Yan L, Shi X, Lou R, Fedorov A, Behnami M, Yuan J, Yang P, Wang B, Cheng JG, Xu Y, Xu Y, Xia W, Pavlovskii N, Peets DC, Zhao W, Wan Y, Burkhardt U, Guo Y, Li S, Felser C, Yang W, Büchner B. Tunable positions of Weyl nodes via magnetism and pressure in the ferromagnetic Weyl semimetal CeAlSi. Nat Commun 2024; 15:1467. [PMID: 38368411 PMCID: PMC10874455 DOI: 10.1038/s41467-024-45658-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 01/30/2024] [Indexed: 02/19/2024] Open
Abstract
The noncentrosymmetric ferromagnetic Weyl semimetal CeAlSi with simultaneous space-inversion and time-reversal symmetry breaking provides a unique platform for exploring novel topological states. Here, by employing multiple experimental techniques, we demonstrate that ferromagnetism and pressure can serve as efficient parameters to tune the positions of Weyl nodes in CeAlSi. At ambient pressure, a magnetism-facilitated anomalous Hall/Nernst effect (AHE/ANE) is uncovered. Angle-resolved photoemission spectroscopy (ARPES) measurements demonstrated that the Weyl nodes with opposite chirality are moving away from each other upon entering the ferromagnetic phase. Under pressure, by tracing the pressure evolution of AHE and band structure, we demonstrate that pressure could also serve as a pivotal knob to tune the positions of Weyl nodes. Moreover, multiple pressure-induced phase transitions are also revealed. These findings indicate that CeAlSi provides a unique and tunable platform for exploring exotic topological physics and electron correlations, as well as catering to potential applications, such as spintronics.
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Affiliation(s)
- Erjian Cheng
- Leibniz Institute for Solid State and Materials Research (IFW-Dresden), 01069, Dresden, Germany.
- Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany.
| | - Limin Yan
- Center for High Pressure Science and Technology Advanced Research, 201203, Shanghai, China
- State Key Laboratory of Superhard Materials, Department of Physics, Jilin University, 130012, Changchun, China
| | - Xianbiao Shi
- State Key Laboratory of Advanced Welding & Joining, Harbin Institute of Technology, 150001, Harbin, China
- Flexible Printed Electronics Technology Center, Harbin Institute of Technology (Shenzhen), 518055, Shenzhen, China
| | - Rui Lou
- Leibniz Institute for Solid State and Materials Research (IFW-Dresden), 01069, Dresden, Germany.
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489, Berlin, Germany.
- Joint Laboratory "Functional Quantum Materials" at BESSY II, 12489, Berlin, Germany.
| | - Alexander Fedorov
- Leibniz Institute for Solid State and Materials Research (IFW-Dresden), 01069, Dresden, Germany
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489, Berlin, Germany
- Joint Laboratory "Functional Quantum Materials" at BESSY II, 12489, Berlin, Germany
| | - Mahdi Behnami
- Leibniz Institute for Solid State and Materials Research (IFW-Dresden), 01069, Dresden, Germany
| | - Jian Yuan
- School of Physical Science and Technology, ShanghaiTech University, 200031, Shanghai, China
| | - Pengtao Yang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, 100190, Beijing, China
- School of Physical Sciences, University of Chinese Academy of Sciences, 100190, Beijing, China
| | - Bosen Wang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, 100190, Beijing, China
- School of Physical Sciences, University of Chinese Academy of Sciences, 100190, Beijing, China
| | - Jin-Guang Cheng
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, 100190, Beijing, China
- School of Physical Sciences, University of Chinese Academy of Sciences, 100190, Beijing, China
| | - Yuanji Xu
- Institute for Applied Physics, University of Science and Technology Beijing, 100083, Beijing, China
| | - Yang Xu
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, 200241, Shanghai, China
| | - Wei Xia
- School of Physical Science and Technology, ShanghaiTech University, 200031, Shanghai, China
| | - Nikolai Pavlovskii
- Institute of Solid State and Materials Physics, Technische Universität Dresden, 01069, Dresden, Germany
| | - Darren C Peets
- Institute of Solid State and Materials Physics, Technische Universität Dresden, 01069, Dresden, Germany
| | - Weiwei Zhao
- State Key Laboratory of Advanced Welding & Joining, Harbin Institute of Technology, 150001, Harbin, China
- Flexible Printed Electronics Technology Center, Harbin Institute of Technology (Shenzhen), 518055, Shenzhen, China
| | - Yimin Wan
- State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, 200438, Shanghai, China
| | - Ulrich Burkhardt
- Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
| | - Yanfeng Guo
- School of Physical Science and Technology, ShanghaiTech University, 200031, Shanghai, China
| | - Shiyan Li
- State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, 200438, Shanghai, China
- Collaborative Innovation Center of Advanced Microstructures, 210093, Nanjing, China
- Shanghai Research Center for Quantum Sciences, 201315, Shanghai, China
| | - Claudia Felser
- Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
| | - Wenge Yang
- Center for High Pressure Science and Technology Advanced Research, 201203, Shanghai, China.
| | - Bernd Büchner
- Leibniz Institute for Solid State and Materials Research (IFW-Dresden), 01069, Dresden, Germany.
- Institute of Solid State and Materials Physics and Würzburg-Dresden Cluster of Excellence-ct.qmat, Technische Universität Dresden, 01062, Dresden, Germany.
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13
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Pan ZC, Li D, Ye XG, Chen Z, Chen ZH, Wang AQ, Tian M, Yao G, Liu K, Liao ZM. Room-temperature orbit-transfer torque enabling van der Waals magnetoresistive memories. Sci Bull (Beijing) 2023; 68:2743-2749. [PMID: 37872061 DOI: 10.1016/j.scib.2023.10.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2023] [Revised: 08/28/2023] [Accepted: 10/09/2023] [Indexed: 10/25/2023]
Abstract
The non-volatile magnetoresistive random access memory (MRAM) is believed to facilitate emerging applications, such as in-memory computing, neuromorphic computing and stochastic computing. Two-dimensional (2D) materials and their van der Waals heterostructures promote the development of MRAM technology, due to their atomically smooth interfaces and tunable physical properties. Here we report the all-2D magnetoresistive memories featuring all-electrical data reading and writing at room temperature based on WTe2/Fe3GaTe2/BN/Fe3GaTe2 heterostructures. The data reading process relies on the tunnel magnetoresistance of Fe3GaTe2/BN/Fe3GaTe2. The data writing is achieved through current induced polarization of orbital magnetic moments in WTe2, which exert torques on Fe3GaTe2, known as the orbit-transfer torque (OTT) effect. In contrast to the conventional reliance on spin moments in spin-transfer torque and spin-orbit torque, the OTT effect leverages the natural out-of-plane orbital moments, facilitating field-free perpendicular magnetization switching through interface currents. Our results indicate that the emerging OTT-MRAM is promising for low-power, high-performance memory applications.
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Affiliation(s)
- Zhen-Cun Pan
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Dong Li
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Xing-Guo Ye
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Zheng Chen
- Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
| | - Zhao-Hui Chen
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - An-Qi Wang
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Mingliang Tian
- Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China; School of Physics and Optoelectronic Engineering, Anhui University, Hefei 230601, China; Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Guangjie Yao
- 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; Hefei National Laboratory, Hefei 230088, China.
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14
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Zhang Y, Xu H, Jia K, Lan G, Huang Z, He B, He C, Shao Q, Wang Y, Zhao M, Ma T, Dong J, Guo C, Cheng C, Feng J, Wan C, Wei H, Shi Y, Zhang G, Han X, Yu G. Room temperature field-free switching of perpendicular magnetization through spin-orbit torque originating from low-symmetry type II Weyl semimetal. SCIENCE ADVANCES 2023; 9:eadg9819. [PMID: 37910619 PMCID: PMC10619928 DOI: 10.1126/sciadv.adg9819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 09/28/2023] [Indexed: 11/03/2023]
Abstract
Spin-orbit torque (SOT) is a promising strategy to deterministically switch the perpendicular magnetization, but usually requires an in-plane magnetic field for breaking the mirror symmetry, which is not suitable for most advanced industrial applications. Van der Waals (vdW) materials with low crystalline symmetry and topological band structures, e.g., Weyl semimetals (WSMs), potentially serve as an outstanding system that may simultaneously realize field-free switching and high energy efficiency. Yet, the demonstration of these superiorities at room temperature has not been realized. Here, we achieve a field-free switching of perpendicular magnetization by using a layered type II WSM, TaIrTe4, in a TaIrTe4/Ti/CoFeB system at room temperature with the critical switching current density ~2.4 × 106 A cm-2. The field-free switching is ascribed to the out-of-plane SOT allowed by the low crystal symmetry. Our work suggests that using low-symmetry materials to generate SOT is a promising route for the manipulation of perpendicular magnetization at room temperature.
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Affiliation(s)
- Yu Zhang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hongjun Xu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - Ke Jia
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Guibin Lan
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhiheng Huang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Bin He
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Congli He
- Institute of Advanced Materials, Beijing Normal University, Beijing 100875, China
| | - Qiming Shao
- Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Yizhan Wang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Mingkun Zhao
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Tianyi Ma
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jing Dong
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Chenyang Guo
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Chen Cheng
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jiafeng Feng
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Caihua Wan
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - Hongxiang Wei
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Youguo Shi
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - Guangyu Zhang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - Xiufeng Han
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - Guoqiang Yu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
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15
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Wang H, Wen Y, Zeng H, Xiong Z, Tu Y, Zhu H, Cheng R, Yin L, Jiang J, Zhai B, Liu C, Shan C, He J. 2D Ferroic Materials for Nonvolatile Memory Applications. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023:e2305044. [PMID: 37486859 DOI: 10.1002/adma.202305044] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2023] [Revised: 07/21/2023] [Indexed: 07/26/2023]
Abstract
The emerging nonvolatile memory technologies based on ferroic materials are promising for producing high-speed, low-power, and high-density memory in the field of integrated circuits. Long-range ferroic orders observed in 2D materials have triggered extensive research interest in 2D magnets, 2D ferroelectrics, 2D multiferroics, and their device applications. Devices based on 2D ferroic materials and heterostructures with an atomically smooth interface and ultrathin thickness have exhibited impressive properties and significant potential for developing advanced nonvolatile memory. In this context, a systematic review of emergent 2D ferroic materials is conducted here, emphasizing their recent research on nonvolatile memory applications, with a view to proposing brighter prospects for 2D magnetic materials, 2D ferroelectric materials, 2D multiferroic materials, and their relevant devices.
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Affiliation(s)
- Hao Wang
- Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan, 430072, China
| | - Yao Wen
- Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan, 430072, China
| | - Hui Zeng
- Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan, 430072, China
| | - Ziren Xiong
- Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan, 430072, China
| | - Yangyuan Tu
- Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan, 430072, China
| | - Hao Zhu
- Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan, 430072, China
| | - Ruiqing Cheng
- Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan, 430072, China
| | - Lei Yin
- Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan, 430072, China
| | - Jian Jiang
- Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan, 430072, China
| | - Baoxing Zhai
- Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan, 430072, China
| | - Chuansheng Liu
- Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan, 430072, China
| | - Chongxin Shan
- Henan Key Laboratory of Diamond Optoelectronic Materials and Devices, Key Laboratory of Material Physics, Ministry of Education, School of Physics, Zhengzhou University, Zhengzhou, 450052, China
| | - Jun He
- Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan, 430072, China
- Hubei Luojia Laboratory, Wuhan, 430079, China
- Wuhan Institute of Quantum Technology, Wuhan, 430206, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100190, China
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16
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Zhang D, Jiang W, Yun H, Benally OJ, Peterson T, Cresswell Z, Fan Y, Lv Y, Yu G, Barriocanal JG, Swatek PW, Mkhoyan KA, Low T, Wang JP. Robust negative longitudinal magnetoresistance and spin-orbit torque in sputtered Pt 3Sn and Pt 3Sn xFe 1-x topological semimetal. Nat Commun 2023; 14:4151. [PMID: 37438330 DOI: 10.1038/s41467-023-39408-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Accepted: 06/13/2023] [Indexed: 07/14/2023] Open
Abstract
Contrary to topological insulators, topological semimetals possess a nontrivial chiral anomaly that leads to negative magnetoresistance and are hosts to both conductive bulk states and topological surface states with intriguing transport properties for spintronics. Here, we fabricate highly-ordered metallic Pt3Sn and Pt3SnxFe1-x thin films via sputtering technology. Systematic angular dependence (both in-plane and out-of-plane) study of magnetoresistance presents surprisingly robust quadratic and linear negative longitudinal magnetoresistance features for Pt3Sn and Pt3SnxFe1-x, respectively. We attribute the anomalous negative longitudinal magnetoresistance to the type-II Dirac semimetal phase (pristine Pt3Sn) and/or the formation of tunable Weyl semimetal phases through symmetry breaking processes, such as magnetic-atom doping, as confirmed by first-principles calculations. Furthermore, Pt3Sn and Pt3SnxFe1-x show the promising performance for facilitating the development of advanced spin-orbit torque devices. These results extend our understanding of chiral anomaly of topological semimetals and can pave the way for exploring novel topological materials for spintronic devices.
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Affiliation(s)
- Delin Zhang
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN, 55455, USA.
| | - Wei Jiang
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Hwanhui Yun
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Onri Jay Benally
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Thomas Peterson
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Zach Cresswell
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Yihong Fan
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Yang Lv
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Guichuan Yu
- Characterization Facility, University of Minnesota, Minneapolis, MN, 55455, USA
| | | | | | - K Andre Mkhoyan
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Tony Low
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN, 55455, USA.
| | - Jian-Ping Wang
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN, 55455, USA.
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, 55455, USA.
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, 55455, USA.
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17
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Sun T, Tang Z, Zang W, Li Z, Li J, Li Z, Cao L, Dominic Rodriguez JS, Mariano COM, Xu H, Lyu P, Hai X, Lin H, Sheng X, Shi J, Zheng Y, Lu YR, He Q, Chen J, Novoselov KS, Chuang CH, Xi S, Luo X, Lu J. Ferromagnetic single-atom spin catalyst for boosting water splitting. NATURE NANOTECHNOLOGY 2023:10.1038/s41565-023-01407-1. [PMID: 37231143 DOI: 10.1038/s41565-023-01407-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 04/20/2023] [Indexed: 05/27/2023]
Abstract
Heterogeneous single-atom spin catalysts combined with magnetic fields provide a powerful means for accelerating chemical reactions with enhanced metal utilization and reaction efficiency. However, designing these catalysts remains challenging due to the need for a high density of atomically dispersed active sites with a short-range quantum spin exchange interaction and long-range ferromagnetic ordering. Here, we devised a scalable hydrothermal approach involving an operando acidic environment for synthesizing various single-atom spin catalysts with widely tunable substitutional magnetic atoms (M1) in a MoS2 host. Among all the M1/MoS2 species, Ni1/MoS2 adopts a distorted tetragonal structure that prompts both ferromagnetic coupling to nearby S atoms as well as adjacent Ni1 sites, resulting in global room-temperature ferromagnetism. Such coupling benefits spin-selective charge transfer in oxygen evolution reactions to produce triplet O2. Furthermore, a mild magnetic field of ~0.5 T enhances the oxygen evolution reaction magnetocurrent by ~2,880% over Ni1/MoS2, leading to excellent activity and stability in both seawater and pure water splitting cells. As supported by operando characterizations and theoretical calculations, a great magnetic-field-enhanced oxygen evolution reaction performance over Ni1/MoS2 is attributed to a field-induced spin alignment and spin density optimization over S active sites arising from field-regulated S(p)-Ni(d) hybridization, which in turn optimizes the adsorption energies for radical intermediates to reduce overall reaction barriers.
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Affiliation(s)
- Tao Sun
- Department of Chemistry, National University of Singapore, Singapore, Singapore
- School of Chemical Engineering, Xi'an Key Laboratory of Special Energy Materials, Northwest University, Xi'an, China
| | - Zhiyuan Tang
- State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices, Centre for Physical Mechanics and Biophysics, School of Physics, Sun Yat-sen University, Guangzhou, China
| | - Wenjie Zang
- Department of Materials Science and Engineering, Faculty of Engineering to College of Design and Engineering, National University of Singapore, Singapore, Singapore
| | - Zejun Li
- School of Physics, Frontiers Science Center for Mobile Information Communication and Security, Southeast University, Nanjing, China
| | - Jing Li
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Zhihao Li
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei, China
| | - Liang Cao
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei, China
| | - Jan Sebastian Dominic Rodriguez
- Department of Physics, Tamkang University, New Taipei City, Taiwan
- Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands
| | | | - Haomin Xu
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Pin Lyu
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Xiao Hai
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Huihui Lin
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Xiaoyu Sheng
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Jiwei Shi
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Yi Zheng
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou, China
| | - Ying-Rui Lu
- National Synchrotron Radiation Research Center, Hsinchu, Taiwan
| | - Qian He
- Department of Materials Science and Engineering, Faculty of Engineering to College of Design and Engineering, National University of Singapore, Singapore, Singapore
| | - Jingsheng Chen
- Department of Materials Science and Engineering, Faculty of Engineering to College of Design and Engineering, National University of Singapore, Singapore, Singapore
| | - Kostya S Novoselov
- Department of Materials Science and Engineering, Faculty of Engineering to College of Design and Engineering, National University of Singapore, Singapore, Singapore
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore, Singapore
| | - Cheng-Hao Chuang
- Department of Physics, Tamkang University, New Taipei City, Taiwan.
| | - Shibo Xi
- Institute of Sustainability for Chemicals, Energy and Environment (ISCE2), Agency for Science, Technology and Research (A*STAR), 1 Pesek Road Jurong Island, Singapore, Singapore.
| | - Xin Luo
- State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices, Centre for Physical Mechanics and Biophysics, School of Physics, Sun Yat-sen University, Guangzhou, China.
| | - Jiong Lu
- Department of Chemistry, National University of Singapore, Singapore, Singapore.
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore, Singapore.
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18
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Dc M, Shao DF, Hou VDH, Vailionis A, Quarterman P, Habiboglu A, Venuti MB, Xue F, Huang YL, Lee CM, Miura M, Kirby B, Bi C, Li X, Deng Y, Lin SJ, Tsai W, Eley S, Wang WG, Borchers JA, Tsymbal EY, Wang SX. Observation of anti-damping spin-orbit torques generated by in-plane and out-of-plane spin polarizations in MnPd 3. NATURE MATERIALS 2023; 22:591-598. [PMID: 37012436 DOI: 10.1038/s41563-023-01522-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Accepted: 03/02/2023] [Indexed: 05/05/2023]
Abstract
Large spin-orbit torques (SOTs) generated by topological materials and heavy metals interfaced with ferromagnets are promising for next-generation magnetic memory and logic devices. SOTs generated from y spin originating from spin Hall and Edelstein effects can realize field-free magnetization switching only when the magnetization and spin are collinear. Here we circumvent the above limitation by utilizing unconventional spins generated in a MnPd3 thin film grown on an oxidized silicon substrate. We observe conventional SOT due to y spin, and out-of-plane and in-plane anti-damping-like torques originated from z spin and x spin, respectively, in MnPd3/CoFeB heterostructures. Notably, we have demonstrated complete field-free switching of perpendicular cobalt via out-of-plane anti-damping-like SOT. Density functional theory calculations show that the observed unconventional torques are due to the low symmetry of the (114)-oriented MnPd3 films. Altogether our results provide a path toward realization of a practical spin channel in ultrafast magnetic memory and logic devices.
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Affiliation(s)
- Mahendra Dc
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA.
| | - Ding-Fu Shao
- Department of Physics and Astronomy & Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, NE, USA
| | | | - Arturas Vailionis
- Stanford Nano Shared Facilities, Stanford University, Stanford, CA, USA
- Department of Physics, Kaunas University of Technology, Kaunas, Lithuania
| | - P Quarterman
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, USA
| | - Ali Habiboglu
- Department of Physics, University of Arizona, Tucson, AZ, USA
| | - M B Venuti
- Department of Physics, Colorado School of Mines, Golden, CO, USA
| | - Fen Xue
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Yen-Lin Huang
- Taiwan Semiconductor Manufacturing Company, Hsinchu, Taiwan
- Department of Materials Science and Engineering, National Yang Ming Chiao Tung University, Hsinchu, Taiwan
| | - Chien-Min Lee
- Taiwan Semiconductor Manufacturing Company, Hsinchu, Taiwan
| | - Masashi Miura
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
- Graduate School of Science and Technology, Seikei University, Tokyo, Japan
| | - Brian Kirby
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, USA
| | - Chong Bi
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Xiang Li
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Yong Deng
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | - Shy-Jay Lin
- Taiwan Semiconductor Manufacturing Company, Hsinchu, Taiwan
| | - Wilman Tsai
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | - Serena Eley
- Department of Physics, Colorado School of Mines, Golden, CO, USA
| | - Wei-Gang Wang
- Department of Physics, University of Arizona, Tucson, AZ, USA
| | - Julie A Borchers
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, USA
| | - Evgeny Y Tsymbal
- Department of Physics and Astronomy & Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, NE, USA
| | - Shan X Wang
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA.
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA.
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19
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Cullen JH, Atencia RB, Culcer D. Spin transfer torques due to the bulk states of topological insulators. NANOSCALE 2023; 15:8437-8446. [PMID: 37096561 DOI: 10.1039/d2nr05176a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Spin torques at topological insulator (TI)/ferromagnet interfaces have received considerable attention in recent years with a view towards achieving full electrical manipulation of magnetic degrees of freedom. The most important question in this field concerns the relative contributions of bulk and surface states to the spin torque, a matter that remains incompletely understood. Whereas the surface state contribution has been extensively studied, the contribution due to the bulk states has received comparatively little attention. Here we study spin torques due to TI bulk states and show that: (i) there is no spin-orbit torque due to the bulk states on a homogeneous magnetisation, in contrast to the surface states, which give rise to a spin-orbit torque via the well-known Edelstein effect. (ii) The bulk states give rise to a spin transfer torque (STT) due to the inhomogeneity of the magnetisation in the vicinity of the interface. This spin transfer torque, which has not been considered in TIs in the past, is somewhat unconventional since it arises from the interplay of the bulk TI spin-orbit coupling and the gradient of the monotonically decaying magnetisation inside the TI. Whereas we consider an idealised model in which the magnetisation gradient is small and the spin transfer torque is correspondingly small, we argue that in real samples the spin transfer torque should be sizable and may provide the dominant contribution due to the bulk states. We show that an experimental smoking gun for identifying the bulk states is the fact that the field-like component of the spin transfer torque generates a spin density with the same size but opposite sign for in-plane and out-of-plane magnetisations. This distinguishes them from the surface states, which are expected to give a spin density of a similar size and the same sign for both an in-plane and out-of-plane magnetisations.
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Affiliation(s)
- James H Cullen
- School of Physics, The University of New South Wales, Sydney 2052, Australia.
| | - Rhonald Burgos Atencia
- School of Physics, The University of New South Wales, Sydney 2052, Australia.
- Facultad de Ingenierías, Departamento de Ciencias Básicas, Universidad del Sinú, Cra.1w No. 38-153, 4536534, Montería, Córdoba 230002, Colombia
| | - Dimitrie Culcer
- School of Physics, The University of New South Wales, Sydney 2052, Australia.
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20
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Kumar D, Chung HJ, Chan J, Jin T, Lim ST, Parkin SSP, Sbiaa R, Piramanayagam SN. Ultralow Energy Domain Wall Device for Spin-Based Neuromorphic Computing. ACS NANO 2023; 17:6261-6274. [PMID: 36944594 DOI: 10.1021/acsnano.2c09744] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Neuromorphic computing (NC) is gaining wide acceptance as a potential technology to achieve low-power intelligent devices. To realize NC, researchers investigate various types of synthetic neurons and synaptic devices, such as memristors and spintronic devices. In comparison, spintronics-based neurons and synapses have potentially higher endurance. However, for realizing low-power devices, domain wall (DW) devices that show DW motion at low energies─typically below pJ/bit─are favored. Here, we demonstrate DW motion at current densities as low as 106 A/m2 by engineering the β-W spin-orbit coupling (SOC) material. With our design, we achieve ultralow pinning fields and current density reduction by a factor of 104. The energy required to move the DW by a distance of about 18.6 μm is 0.4 fJ, which translates into the energy consumption of 27 aJ/bit for a bit-length of 1 μm. With a meander DW device configuration, we have established a controlled DW motion for synapse applications and have shown the direction to make ultralow energy spin-based neuromorphic elements.
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Affiliation(s)
- Durgesh Kumar
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371, Singapore
| | - Hong Jing Chung
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis, 138634, Singapore
| | - JianPeng Chan
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371, Singapore
| | - Tianli Jin
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371, Singapore
| | - Sze Ter Lim
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis, 138634, Singapore
| | - Stuart S P Parkin
- Max Planck Institute for Microstructure Physics, 06120 Halle, Germany
| | - Rachid Sbiaa
- Department of Physics, Sultan Qaboos University, P.O. Box 36, PC 123, Muscat, Oman
| | - S N Piramanayagam
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371, Singapore
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21
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Zhao T, Liu L, Zhou C, Zheng Z, Li H, Xie Q, Yao B, Ren L, Chai J, Dong Z, Zhao C, Chen J. Enhancement of Out-of-Plane Spin-Orbit Torque by Interfacial Modification. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2208954. [PMID: 36647621 DOI: 10.1002/adma.202208954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 01/09/2023] [Indexed: 06/17/2023]
Abstract
Spin-orbit torque (SOT)-induced switching of perpendicular magnetization in the absence of magnetic field is crucial for the application of SOT-based spintronic devices. Recent works have demonstrated that the low-symmetry crystal structure in CuPt/CoPt can give rise to an out-of-plane (OOP) spin torque and lead to deterministic magnetization switching without an external field. However, it is essential to improve OOP effective field for the efficient switching. In this work, the impact of interface oxidation on the generation of OOP effective field in a CuPt/ferromagnet heterostructure is systematically studied. By introducing an oxidized CuPt surface, it is found that the field-free switching performance shows remarkable improvement. OOP effective field measurement indicates that the oxidation treatment can enhance the OOP effective field by more than two times. It is also demonstrated that this oxidation-induced OOP SOT efficiency enhancement is independent of the device shapes, magnetic materials, or magnetization easy axis. This work contributes to improve the performance of SOT devices and provides an effective fabrication guidance for future spintronic devices that utilize OOP SOT.
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Affiliation(s)
- Tieyang Zhao
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Liang Liu
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Chenghang Zhou
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Zhenyi Zheng
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Huihui Li
- Beijing Superstring Academy of Memory Technology, Beijing, 100176, China
| | - Qidong Xie
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Bingqing Yao
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Lizhu Ren
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Jianwei Chai
- Institute of Materials Research and Engineering (IMRE), A*STAR (Agency for Science, Technology and Research), Singapore, 138634, Singapore
| | - Zhili Dong
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Chao Zhao
- Beijing Superstring Academy of Memory Technology, Beijing, 100176, China
| | - Jingsheng Chen
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
- Institute of Materials Research and Engineering (IMRE), A*STAR (Agency for Science, Technology and Research), Singapore, 138634, Singapore
- Chongqing Research Institute, National University of Singapore, Chongqing, 401120, China
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22
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Sun W, Chen Y, Zhuang W, Chen Z, Song A, Liu R, Wang X. Sizable spin-to-charge conversion in PLD-grown amorphous (Mo, W)Te 2-xfilms. NANOTECHNOLOGY 2023; 34:135001. [PMID: 36584386 DOI: 10.1088/1361-6528/acaf34] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 12/29/2022] [Indexed: 06/17/2023]
Abstract
We report on the spin-to-charge conversion (SCC) in Mo0.25W0.75Te2-x(MWT)/Y3Fe5O12(YIG) heterostructures at room temperature. The centimeter-scale amorphous MWT films are deposited on liquid-phase-epitaxial YIG by pulsed laser deposition technique. The significant SCC voltage is measured in the MWT layer with a sizable spin Hall angle of ∼0.021 by spin pumping experiments. The control experiments by inserting MgO or Ag layer between MWT and YIG show that the SCC is mainly attributed to the inverse spin Hall effect rather than the thermal or interfacial Rashba effect. Our work provides a novel spin-source material for energy-efficient topological spintronic devices.
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Affiliation(s)
- Wenxuan Sun
- Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
| | - Yequan Chen
- Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
| | - Wenzhuo Zhuang
- Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
| | - Zhongqiang Chen
- Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
| | - Anke Song
- Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
| | - Ruxin Liu
- Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
| | - Xuefeng Wang
- Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
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23
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Hori T, Kanazawa N, Hirayama M, Fujiwara K, Tsukazaki A, Ichikawa M, Kawasaki M, Tokura Y. A Noble-Metal-Free Spintronic System with Proximity-Enhanced Ferromagnetic Topological Surface State of FeSi above Room Temperature. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2206801. [PMID: 36333884 DOI: 10.1002/adma.202206801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 10/14/2022] [Indexed: 06/16/2023]
Abstract
Strongly spin-orbit coupled states at metal interfaces, topological insulators, and 2D materials enable efficient electric control of spin states, offering great potential for spintronics. However, there are still materials challenges to overcome, including the integration into advanced silicon electronics and the scarce resources of constituent heavy elements of those materials. Through magneto-transport measurements and first-principles calculations, here robust spin-orbit coupling (SOC)-induced properties of a ferromagnetic topological surface state in FeSi and their controllability via hybridization with adjacent materials are demonstrated. In comparison to the case of its naturally oxidized surface, the ferromagnetic transition temperature is greatly increased beyond room temperature and the effective SOC strength is almost doubled at the surface in proximity to a wide-bandgap fluoride insulator. Those enhanced magnetic properties enable room-temperature magnetization switching, being applicable to spin-orbit torque based spintronic devices. Realization of strong SOC in the noble-metal-free silicon-based compound will accelerate spintronic applications.
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Affiliation(s)
- Tomohiro Hori
- Department of Applied Physics, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo, 113-8656, Japan
| | - Naoya Kanazawa
- Department of Applied Physics, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo, 113-8656, Japan
| | - Motoaki Hirayama
- Department of Applied Physics, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo, 113-8656, Japan
- RIKEN Center for Emergent Matter Science (CEMS), Hirosawa 2-1, Wako, Saitama, 351-0198, Japan
| | - Kohei Fujiwara
- Institute for Materials Research, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai, Miyagi, 980-8577, Japan
| | - Atsushi Tsukazaki
- Institute for Materials Research, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai, Miyagi, 980-8577, Japan
| | - Masakazu Ichikawa
- Department of Applied Physics, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo, 113-8656, Japan
| | - Masashi Kawasaki
- Department of Applied Physics, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo, 113-8656, Japan
- RIKEN Center for Emergent Matter Science (CEMS), Hirosawa 2-1, Wako, Saitama, 351-0198, Japan
| | - Yoshinori Tokura
- Department of Applied Physics, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo, 113-8656, Japan
- RIKEN Center for Emergent Matter Science (CEMS), Hirosawa 2-1, Wako, Saitama, 351-0198, Japan
- Tokyo College, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo, 113-8656, Japan
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24
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Wang L, Xiong J, Cheng B, Dai Y, Wang F, Pan C, Cao T, Liu X, Wang P, Chen M, Yan S, Liu Z, Xiao J, Xu X, Wang Z, Shi Y, Cheong SW, Zhang H, Liang SJ, Miao F. Cascadable in-memory computing based on symmetric writing and readout. SCIENCE ADVANCES 2022; 8:eabq6833. [PMID: 36490344 PMCID: PMC11324065 DOI: 10.1126/sciadv.abq6833] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Accepted: 11/04/2022] [Indexed: 06/17/2023]
Abstract
The building block of in-memory computing with spintronic devices is mainly based on the magnetic tunnel junction with perpendicular interfacial anisotropy (p-MTJ). The resulting asymmetric write and readout operations impose challenges in downscaling and direct cascadability of p-MTJ devices. Here, we propose that a previously unimplemented symmetric write and readout mechanism can be realized in perpendicular-anisotropy spin-orbit (PASO) quantum materials based on Fe3GeTe2 and WTe2. We demonstrate that field-free and deterministic reversal of the perpendicular magnetization can be achieved using unconventional charge-to-z-spin conversion. The resulting magnetic state can be readily probed with its intrinsic inverse process, i.e., z-spin-to-charge conversion. Using the PASO quantum material as a fundamental building block, we implement the functionally complete set of logic-in-memory operations and a more complex nonvolatile half-adder logic function. Our work highlights the potential of PASO quantum materials for the development of scalable energy-efficient and ultrafast spintronic computing.
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Affiliation(s)
- 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
| | - 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
| | - Bin Cheng
- Institute of Interdisciplinary Physical Sciences, School of Science, Nanjing University of Science and Technology, Nanjing 210094, China
| | - 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
| | - Fuyi 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
| | - Chen Pan
- Institute of Interdisciplinary Physical Sciences, School of Science, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Tianjun Cao
- 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
| | - Xiaowei 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
| | - 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
| | - Moyu Chen
- 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
| | - 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
| | - Jingjing Xiao
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, 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
| | - Zhenlin 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
| | - Youguo Shi
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, 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
| | - Haijun Zhang
- 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
| | - 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
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25
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Zhang G, Wu H, Zhang L, Yang L, Xie Y, Guo F, Li H, Tao B, Wang G, Zhang W, Chang H. Two-Dimensional Van Der Waals Topological Materials: Preparation, Properties, and Device Applications. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2204380. [PMID: 36135779 DOI: 10.1002/smll.202204380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 08/23/2022] [Indexed: 06/16/2023]
Abstract
Over the past decade, 2D van der Waals (vdW) topological materials (TMs), including topological insulators and topological semimetals, which combine atomically flat 2D layers and topologically nontrivial band structures, have attracted increasing attention in condensed-matter physics and materials science. These easily cleavable and integrated TMs provide the ideal platform for exploring topological physics in the 2D limit, where new physical phenomena may emerge, and represent a potential to control and investigate exotic properties and device applications in nanoscale topological phases. However, multifaced efforts are still necessary, which is the prerequisite for the practical application of 2D vdW TMs. Herein, this review focuses on the preparation, properties, and device applications of 2D vdW TMs. First, three common preparation strategies for 2D vdW TMs are summarized, including single crystal exfoliation, chemical vapor deposition, and molecular beam epitaxy. Second, the origin and regulation of various properties of 2D vdW TMs are introduced, involving electronic properties, transport properties, optoelectronic properties, thermoelectricity, ferroelectricity, and magnetism. Third, some device applications of 2D vdW TMs are presented, including field-effect transistors, memories, spintronic devices, and photodetectors. Finally, some significant challenges and opportunities for the practical application of 2D vdW TMs in 2D topological electronics are briefly addressed.
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Affiliation(s)
- Gaojie Zhang
- Quantum-Nano Matter and Device Lab, Center for Joining and Electronic Packaging, State Key Laboratory of Material Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
- Institute for Quantum Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Hao Wu
- Quantum-Nano Matter and Device Lab, Center for Joining and Electronic Packaging, State Key Laboratory of Material Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
- Institute for Quantum Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Liang Zhang
- Liuzhou Key Laboratory for New Energy Vehicle Power Lithium Battery, School of Microelectronics and Engineering, Guangxi University of Science and Technology, Liuzhou, 545006, China
| | - Li Yang
- Quantum-Nano Matter and Device Lab, Center for Joining and Electronic Packaging, State Key Laboratory of Material Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
- Institute for Quantum Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Yuanmiao Xie
- Liuzhou Key Laboratory for New Energy Vehicle Power Lithium Battery, School of Microelectronics and Engineering, Guangxi University of Science and Technology, Liuzhou, 545006, China
| | - Fei Guo
- Liuzhou Key Laboratory for New Energy Vehicle Power Lithium Battery, School of Microelectronics and Engineering, Guangxi University of Science and Technology, Liuzhou, 545006, China
| | - Hongda Li
- Liuzhou Key Laboratory for New Energy Vehicle Power Lithium Battery, School of Microelectronics and Engineering, Guangxi University of Science and Technology, Liuzhou, 545006, China
| | - Boran Tao
- Liuzhou Key Laboratory for New Energy Vehicle Power Lithium Battery, School of Microelectronics and Engineering, Guangxi University of Science and Technology, Liuzhou, 545006, China
| | - Guofu Wang
- Liuzhou Key Laboratory for New Energy Vehicle Power Lithium Battery, School of Microelectronics and Engineering, Guangxi University of Science and Technology, Liuzhou, 545006, China
| | - Wenfeng Zhang
- Quantum-Nano Matter and Device Lab, Center for Joining and Electronic Packaging, State Key Laboratory of Material Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
- Institute for Quantum Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
- Shenzhen R&D Center of Huazhong University of Science and Technology (HUST), Shenzhen, 518000, China
| | - Haixin Chang
- Quantum-Nano Matter and Device Lab, Center for Joining and Electronic Packaging, State Key Laboratory of Material Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
- Institute for Quantum Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
- Shenzhen R&D Center of Huazhong University of Science and Technology (HUST), Shenzhen, 518000, China
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26
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Kao IH, Muzzio R, Zhang H, Zhu M, Gobbo J, Yuan S, Weber D, Rao R, Li J, Edgar JH, Goldberger JE, Yan J, Mandrus DG, Hwang J, Cheng R, Katoch J, Singh S. Deterministic switching of a perpendicularly polarized magnet using unconventional spin-orbit torques in WTe 2. NATURE MATERIALS 2022; 21:1029-1034. [PMID: 35710631 DOI: 10.1038/s41563-022-01275-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Accepted: 05/03/2022] [Indexed: 06/15/2023]
Abstract
Spin-orbit torque (SOT)-driven deterministic control of the magnetic state of a ferromagnet with perpendicular magnetic anisotropy is key to next-generation spintronic applications including non-volatile, ultrafast and energy-efficient data-storage devices. However, field-free deterministic switching of perpendicular magnetization remains a challenge because it requires an out-of-plane antidamping torque, which is not allowed in conventional spin-source materials such as heavy metals and topological insulators due to the system's symmetry. The exploitation of low-crystal symmetries in emergent quantum materials offers a unique approach to achieve SOTs with unconventional forms. Here we report an experimental realization of field-free deterministic magnetic switching of a perpendicularly polarized van der Waals magnet employing an out-of-plane antidamping SOT generated in layered WTe2, a quantum material with a low-symmetry crystal structure. Our numerical simulations suggest that the out-of-plane antidamping torque in WTe2 is essential to explain the observed magnetization switching.
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Affiliation(s)
- I-Hsuan Kao
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Ryan Muzzio
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Hantao Zhang
- Department of Electrical and Computer Engineering, University of California Riverside, Riverside, CA, USA
| | - Menglin Zhu
- Department of Materials Science and Engineering, The Ohio State University, Columbus, OH, USA
| | - Jacob Gobbo
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Sean Yuan
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Daniel Weber
- Department of Chemistry, The Ohio State University, Columbus, OH, USA
- Battery and Electrochemistry Laboratory (BELLA), Institute of Nanotechnology, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Rahul Rao
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Dayton, OH, USA
| | - Jiahan Li
- Tim Taylor Department of Chemical Engineering, Kansas State University, Manhattan, KS, USA
| | - James H Edgar
- Tim Taylor Department of Chemical Engineering, Kansas State University, Manhattan, KS, USA
| | | | - Jiaqiang Yan
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
- Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN, USA
| | - David G Mandrus
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
- Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN, USA
| | - Jinwoo Hwang
- Department of Materials Science and Engineering, The Ohio State University, Columbus, OH, USA
| | - Ran Cheng
- Department of Electrical and Computer Engineering, University of California Riverside, Riverside, CA, USA
- Department of Physics and Astronomy, University of California Riverside, Riverside, CA, USA
| | - Jyoti Katoch
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Simranjeet Singh
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA, USA.
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27
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Zhou X, Zhang RW, Yang X, Li XP, Feng W, Mokrousov Y, Yao Y. Disorder- and Topology-Enhanced Fully Spin-Polarized Currents in Nodal Chain Spin-Gapless Semimetals. PHYSICAL REVIEW LETTERS 2022; 129:097201. [PMID: 36083680 DOI: 10.1103/physrevlett.129.097201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 04/27/2022] [Accepted: 08/03/2022] [Indexed: 06/15/2023]
Abstract
Recently discovered high-quality nodal chain spin-gapless semimetals MF_{3} (M=Pd, Mn) feature an ultraclean nodal chain in the spin up channel residing right at the Fermi level and displaying a large spin gap leading to a 100% spin polarization of transport properties. Here, we investigate both intrinsic and extrinsic contributions to anomalous and spin transport in this class of materials. The dominant intrinsic origin is found to originate entirely from the gapped nodal chains without the entanglement of any other trivial bands. The side-jump mechanism is predicted to be negligibly small, but intrinsic skew scattering enhances the intrinsic Hall and Nernst signals significantly, leading to large values of respective conductivities. Our findings open a new material platform for exploring strong anomalous and spin transport properties in magnetic topological semimetals.
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Affiliation(s)
- Xiaodong Zhou
- 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, School of Physics, Beijing Institute of Technology, Beijing 100081, China
| | - Run-Wu Zhang
- 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, School of Physics, Beijing Institute of Technology, Beijing 100081, China
| | - Xiuxian Yang
- 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, School of Physics, Beijing Institute of Technology, Beijing 100081, China
| | - Xiao-Ping Li
- 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, School of Physics, Beijing Institute of Technology, Beijing 100081, China
| | - Wanxiang Feng
- 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, School of Physics, Beijing Institute of Technology, Beijing 100081, China
| | - Yuriy Mokrousov
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425 Jülich, Germany
- Institute of Physics, Johannes Gutenberg University Mainz, 55099 Mainz, Germany
| | - 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, School of Physics, Beijing Institute of Technology, Beijing 100081, China
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28
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Magnetic NiFe thin films composing MoS 2 nanostructures for spintronic application. Sci Rep 2022; 12:9809. [PMID: 35697928 PMCID: PMC9192644 DOI: 10.1038/s41598-022-14060-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Accepted: 05/31/2022] [Indexed: 11/25/2022] Open
Abstract
We demonstrate a nanostructure layer made of Ni80Fe20 (permalloy:Py) thin film conjugated MoS2 nano-flakes. Layers are made based on a single-step co-deposition of Py and MoS2 from a single solution where ionic Ni and Fe and MoS2 flakes co-exist. Synthesized thin films with MoS2 flakes show increasing coercivity and enhancement in magneto-optical Kerr effect. Ferromagnetic resonance linewidth as well as the damping parameter increaseed significantly compared to that of the Py layer due to the presence of MoS2. Raman spectroscopy and elemental mapping is used to show the quality of MoS2 within the Py thin film. Our synthesis method promises new opportunities for electrochemical production of functional spintronic-based devices.
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29
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Two-dimensional materials prospects for non-volatile spintronic memories. Nature 2022; 606:663-673. [PMID: 35732761 DOI: 10.1038/s41586-022-04768-0] [Citation(s) in RCA: 63] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 04/19/2022] [Indexed: 01/12/2023]
Abstract
Non-volatile magnetic random-access memories (MRAMs), such as spin-transfer torque MRAM and next-generation spin-orbit torque MRAM, are emerging as key to enabling low-power technologies, which are expected to spread over large markets from embedded memories to the Internet of Things. Concurrently, the development and performances of devices based on two-dimensional van der Waals heterostructures bring ultracompact multilayer compounds with unprecedented material-engineering capabilities. Here we provide an overview of the current developments and challenges in regard to MRAM, and then outline the opportunities that can arise by incorporating two-dimensional material technologies. We highlight the fundamental properties of atomically smooth interfaces, the reduced material intermixing, the crystal symmetries and the proximity effects as the key drivers for possible disruptive improvements for MRAM at advanced technology nodes.
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30
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Calavalle F, Suárez-Rodríguez M, Martín-García B, Johansson A, Vaz DC, Yang H, Maznichenko IV, Ostanin S, Mateo-Alonso A, Chuvilin A, Mertig I, Gobbi M, Casanova F, Hueso LE. Gate-tuneable and chirality-dependent charge-to-spin conversion in tellurium nanowires. NATURE MATERIALS 2022; 21:526-532. [PMID: 35256792 DOI: 10.1038/s41563-022-01211-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2021] [Accepted: 01/24/2022] [Indexed: 06/14/2023]
Abstract
Chiral materials are an ideal playground for exploring the relation between symmetry, relativistic effects and electronic transport. For instance, chiral organic molecules have been intensively studied to electrically generate spin-polarized currents in the last decade, but their poor electronic conductivity limits their potential for applications. Conversely, chiral inorganic materials such as tellurium have excellent electrical conductivity, but their potential for enabling the electrical control of spin polarization in devices remains unclear. Here, we demonstrate the all-electrical generation, manipulation and detection of spin polarization in chiral single-crystalline tellurium nanowires. By recording a large (up to 7%) and chirality-dependent unidirectional magnetoresistance, we show that the orientation of the electrically generated spin polarization is determined by the nanowire handedness and uniquely follows the current direction, while its magnitude can be manipulated by an electrostatic gate. Our results pave the way for the development of magnet-free chirality-based spintronic devices.
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Affiliation(s)
| | | | | | - Annika Johansson
- Institute of Physics, Martin Luther University Halle-Wittenberg, Halle, Germany
- Max Planck Institute of Microstructure Physics, Halle, Germany
| | - Diogo C Vaz
- CIC nanoGUNE BRTA, Donostia-San Sebastian, Spain
| | - Haozhe Yang
- CIC nanoGUNE BRTA, Donostia-San Sebastian, Spain
| | - Igor V Maznichenko
- Institute of Physics, Martin Luther University Halle-Wittenberg, Halle, Germany
| | - Sergey Ostanin
- Institute of Physics, Martin Luther University Halle-Wittenberg, Halle, Germany
| | - Aurelio Mateo-Alonso
- IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
- POLYMAT, University of the Basque Country UPV/EHU, Donostia-San Sebastian, Spain
| | - Andrey Chuvilin
- CIC nanoGUNE BRTA, Donostia-San Sebastian, Spain
- IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
| | - Ingrid Mertig
- Institute of Physics, Martin Luther University Halle-Wittenberg, Halle, Germany
| | - Marco Gobbi
- CIC nanoGUNE BRTA, Donostia-San Sebastian, Spain.
- IKERBASQUE, Basque Foundation for Science, Bilbao, Spain.
- Centro de Física de Materiales CSIC-UPV/EHU, Donostia-San Sebastian, Spain.
| | - Fèlix Casanova
- CIC nanoGUNE BRTA, Donostia-San Sebastian, Spain.
- IKERBASQUE, Basque Foundation for Science, Bilbao, Spain.
| | - Luis E Hueso
- CIC nanoGUNE BRTA, Donostia-San Sebastian, Spain.
- IKERBASQUE, Basque Foundation for Science, Bilbao, Spain.
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31
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Efficient spin current source using a half-Heusler alloy topological semimetal with back end of line compatibility. Sci Rep 2022; 12:2426. [PMID: 35165335 PMCID: PMC8844406 DOI: 10.1038/s41598-022-06325-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 01/27/2022] [Indexed: 11/16/2022] Open
Abstract
Topological materials, such as topological insulators (TIs), have great potential for ultralow power spintronic devices, thanks to their giant spin Hall effect. However, the giant spin Hall angle (θSH > 1) is limited to a few chalcogenide TIs with toxic elements and low melting points, making them challenging for device integration during the silicon Back-End-of-Line (BEOL) process. Here, we show that by using a half-Heusler alloy topological semi-metal (HHA-TSM), YPtBi, it is possible to achieve both a giant θSH up to 4.1 and a high thermal budget up to 600 °C. We demonstrate magnetization switching of a CoPt thin film using the giant spin Hall effect of YPtBi by current densities lower than those of heavy metals by one order of magnitude. Since HHA-TSM includes a group of three-element topological materials with great flexibility, our work opens the door to the third-generation spin Hall materials with both high θSH and high compatibility with the BEOL process that would be easily adopted by the industry.
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32
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Wu G, Wang D, Verma N, Rao R, Cheng Y, Guo S, Cao G, Watanabe K, Taniguchi T, Lau CN, Yang F, Randeria M, Bockrath M, Hammel PC. Enhancing Perpendicular Magnetic Anisotropy in Garnet Ferrimagnet by Interfacing with Few-Layer WTe 2. NANO LETTERS 2022; 22:1115-1121. [PMID: 35099980 DOI: 10.1021/acs.nanolett.1c04237] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Engineering magnetic anisotropy in a ferro- or ferrimagnetic (FM) thin film is crucial in a spintronic device. One way to modify the magnetic anisotropy is through the surface of the FM thin film. Here, we report the emergence of a perpendicular magnetic anisotropy (PMA) induced by interfacial interactions in a heterostructure comprised of a garnet ferrimagnet, Y3Fe5O12 (YIG), and a low-symmetry, high spin-orbit coupling (SOC) transition metal dichalcogenide, WTe2. At the same time, we also observed an enhancement in Gilbert damping in the WTe2-covered YIG area. Both the magnitude of interface-induced PMA and the Gilbert damping enhancement have no observable WTe2 thickness dependence down to a single quadruple layer, indicating that the interfacial interaction plays a critical role. The ability of WTe2 to enhance the PMA in FM thin film, combined with its previously reported capability to generate out-of-plane damping like spin torque, makes it desirable for magnetic memory applications.
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Affiliation(s)
- Guanzhong Wu
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, United States
| | - Dongying Wang
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, United States
| | - Nishchhal Verma
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, United States
| | - Rahul Rao
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Dayton, Ohio 45433, United States
| | - Yang Cheng
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, United States
| | - Side Guo
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, United States
| | - Guixin Cao
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, United States
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Chun Ning Lau
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, United States
| | - Fengyuan Yang
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, United States
| | - Mohit Randeria
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, United States
| | - Marc Bockrath
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, United States
| | - P Chris Hammel
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, United States
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33
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Shin I, Cho WJ, An ES, Park S, Jeong HW, Jang S, Baek WJ, Park SY, Yang DH, Seo JH, Kim GY, Ali MN, Choi SY, Lee HW, Kim JS, Kim SD, Lee GH. Spin-Orbit Torque Switching in an All-Van der Waals Heterostructure. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2101730. [PMID: 34908193 DOI: 10.1002/adma.202101730] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 12/09/2021] [Indexed: 06/14/2023]
Abstract
Current-induced control of magnetization in ferromagnets using spin-orbit torque (SOT) has drawn attention as a new mechanism for fast and energy efficient magnetic memory devices. Energy-efficient spintronic devices require a spin-current source with a large SOT efficiency (ξ) and electrical conductivity (σ), and an efficient spin injection across a transparent interface. Herein, single crystals of the van der Waals (vdW) topological semimetal WTe2 and vdW ferromagnet Fe3 GeTe2 are used to satisfy the requirements in their all-vdW-heterostructure with an atomically sharp interface. The results exhibit values of ξ ≈ 4.6 and σ ≈ 2.25 × 105 Ω-1 m-1 for WTe2 . Moreover, the significantly reduced switching current density of 3.90 × 106 A cm-2 at 150 K is obtained, which is an order of magnitude smaller than those of conventional heavy-metal/ferromagnet thin films. These findings highlight that engineering vdW-type topological materials and magnets offers a promising route to energy-efficient magnetization control in SOT-based spintronics.
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Affiliation(s)
- Inseob Shin
- Department of Physics, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
| | - Won Joon Cho
- Material Research Center, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics Co., Ltd., 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do, 16678, Republic of Korea
| | - Eun-Su An
- Department of Physics, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang, 37673, Republic of Korea
| | - Sungyu Park
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang, 37673, Republic of Korea
| | - Hyeon-Woo Jeong
- Department of Physics, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
| | - Seong Jang
- Department of Physics, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
| | - Woon Joong Baek
- Material Research Center, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics Co., Ltd., 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do, 16678, Republic of Korea
| | - Seong Yong Park
- Material Research Center, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics Co., Ltd., 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do, 16678, Republic of Korea
| | - Dong-Hwan Yang
- Department of Materials Science and Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Pohang, 37673, Republic of Korea
| | - Jun Ho Seo
- Department of Physics, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
| | - Gi-Yeop Kim
- Department of Materials Science and Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Pohang, 37673, Republic of Korea
| | - Mazhar N Ali
- Max Plank Institute for Microstructure Physics, Weinberg 2, 06120, Halle (Saale), Germany
| | - Si-Young Choi
- Department of Materials Science and Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Pohang, 37673, Republic of Korea
| | - Hyun-Woo Lee
- Department of Physics, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
- Asia Pacific Center for Theoretical Physics, 77 Cheongam-Ro, Pohang, 37673, Republic of Korea
| | - Jun Sung Kim
- Department of Physics, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang, 37673, Republic of Korea
| | - Sung Dug Kim
- Material Research Center, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics Co., Ltd., 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do, 16678, Republic of Korea
| | - Gil-Ho Lee
- Department of Physics, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
- Asia Pacific Center for Theoretical Physics, 77 Cheongam-Ro, Pohang, 37673, Republic of Korea
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34
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Zhou R, Wu J, Chen Y, Xie L. Polymorph Structures, Rich Physical Properties and Potential Applications of
Two‐Dimensional MoTe
2
,
WTe
2
and Its Alloys. CHINESE J CHEM 2022. [DOI: 10.1002/cjoc.202100777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Rui Zhou
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, National Center for Nanoscience and Technology Beijing 100190 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Juanxia Wu
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, National Center for Nanoscience and Technology Beijing 100190 China
| | - Yuansha Chen
- Beijing National Laboratory for Condensed Matter Physics & Institute of Physics, Chinese Academy of Sciences Beijing 100190 China
| | - Liming Xie
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, National Center for Nanoscience and Technology Beijing 100190 China
- University of Chinese Academy of Sciences Beijing 100049 China
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35
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You Y, Bai H, Feng X, Fan X, Han L, Zhou X, Zhou Y, Zhang R, Chen T, Pan F, Song C. Cluster magnetic octupole induced out-of-plane spin polarization in antiperovskite antiferromagnet. Nat Commun 2021; 12:6524. [PMID: 34764284 PMCID: PMC8585975 DOI: 10.1038/s41467-021-26893-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Accepted: 10/26/2021] [Indexed: 11/09/2022] Open
Abstract
Out-of-plane spin polarization σz has attracted increasing interests of researchers recently, due to its potential in high-density and low-power spintronic devices. Noncollinear antiferromagnet (AFM), which has unique 120° triangular spin configuration, has been discovered to possess σz. However, the physical origin of σz in noncollinear AFM is still not clear, and the external magnetic field-free switching of perpendicular magnetic layer using the corresponding σz has not been reported yet. Here, we use the cluster magnetic octupole in antiperovskite AFM Mn3SnN to demonstrate the generation of σz. σz is induced by the precession of carrier spins when currents flow through the cluster magnetic octupole, which also relies on the direction of the cluster magnetic octupole in conjunction with the applied current. With the aid of σz, current induced spin-orbit torque (SOT) switching of adjacent perpendicular ferromagnet is realized without external magnetic field. Our findings present a new perspective to the generation of out-of-plane spin polarizations via noncollinear AFM spin structure, and provide a potential path to realize ultrafast high-density applications.
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Affiliation(s)
- Yunfeng You
- Key Laboratory of Advanced Materials, School of Materials Science and Engineering, Tsinghua University, Beijing, 100084, China
| | - Hua Bai
- Key Laboratory of Advanced Materials, School of Materials Science and Engineering, Tsinghua University, Beijing, 100084, China
| | - Xiaoyu Feng
- The Key Lab for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou, 730000, China
| | - Xiaolong Fan
- The Key Lab for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou, 730000, China
| | - Lei Han
- Key Laboratory of Advanced Materials, School of Materials Science and Engineering, Tsinghua University, Beijing, 100084, China
| | - Xiaofeng Zhou
- Key Laboratory of Advanced Materials, School of Materials Science and Engineering, Tsinghua University, Beijing, 100084, China
| | - Yongjian Zhou
- Key Laboratory of Advanced Materials, School of Materials Science and Engineering, Tsinghua University, Beijing, 100084, China
| | - Ruiqi Zhang
- Key Laboratory of Advanced Materials, School of Materials Science and Engineering, Tsinghua University, Beijing, 100084, China
| | - Tongjin Chen
- Key Laboratory of Advanced Materials, School of Materials Science and Engineering, Tsinghua University, Beijing, 100084, China
| | - Feng Pan
- Key Laboratory of Advanced Materials, School of Materials Science and Engineering, Tsinghua University, Beijing, 100084, China
| | - Cheng Song
- Key Laboratory of Advanced Materials, School of Materials Science and Engineering, Tsinghua University, Beijing, 100084, China.
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36
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Tang W, Liu H, Li Z, Pan A, Zeng Y. Spin-Orbit Torque in Van der Waals-Layered Materials and Heterostructures. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:e2100847. [PMID: 34323390 PMCID: PMC8456225 DOI: 10.1002/advs.202100847] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 06/03/2021] [Indexed: 06/13/2023]
Abstract
Spin-orbit torque (SOT) opens an efficient and versatile avenue for the electrical manipulation of magnetization in spintronic devices. The enhancement of SOT efficiency and reduction of power consumption are key points for the implementation of high-performance SOT devices, which strongly rely on the spin-orbit coupling (SOC) strength and magnetic properties of ferromagnetic/non-magnetic heterostructures. Recently, van der Waals-layered materials have shown appealing properties for use in efficient SOT applications. On the one hand, transition-metal dichalcogenides, topological insulators, and graphene-based heterostructures possess appreciable SOC strength. This feature can efficiently converse the charge current into spin current and result in large SOT. On the other hand, the newly discovered layered magnetic materials provide ultra-thin and gate-tunable ferromagnetic candidates for high-performance SOT devices. In this review, the latest advancements of SOT research in various layered materials are summarized. First, a brief introduction of SOT is given. Second, SOT studies of various layered materials and heterostructures are summarized. Subsequently, progresses on SOT-induced magnetization switching are presented. Finally, current challenges and prospects for future development are suggested.
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Affiliation(s)
- Wei Tang
- Key laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong ProvinceCollege of Physics and Optoelectronic EngineeringShenzhen UniversityShenzhen518060China
| | - Haoliang Liu
- State Key Laboratory on Tunable Laser TechnologyMinistry of Industry and Information Technology Key Lab of Micro‐Nano Optoelectronic Information SystemSchool of ScienceHarbin Institute of TechnologyShenzhen518055China
| | - Zhe Li
- State Key Laboratory on Tunable Laser TechnologyMinistry of Industry and Information Technology Key Lab of Micro‐Nano Optoelectronic Information SystemSchool of ScienceHarbin Institute of TechnologyShenzhen518055China
| | - Anlian Pan
- Key Laboratory for Micro‐Nano Physics and Technology of Hunan ProvinceCollege of Materials Science and EngineeringHunan UniversityChangsha410082China
| | - Yu‐Jia Zeng
- Key laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong ProvinceCollege of Physics and Optoelectronic EngineeringShenzhen UniversityShenzhen518060China
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37
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Tian M, Zhu Y, Jalali M, Jiang W, Liang J, Huang Z, Chen Q, Zeng Z, Zhai Y. Two-Dimensional Van Der Waals Materials for Spin-Orbit Torque Applications. FRONTIERS IN NANOTECHNOLOGY 2021. [DOI: 10.3389/fnano.2021.732916] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Spin-orbit torque (SOT) provides an efficient approach to control the magnetic state and dynamics in different classes of materials. Recent years, the crossover between two-dimensional van der Waals (2D vdW) materials and SOT opens a new prospect to push SOT devices to the 2D limit. In this mini-review, we summarize the latest progress in 2D vdW materials for SOT applications, highlighting the comparison of the performance between devices with various structures. It is prospected that the large family of 2D vdW materials and numerous combinations of heterostructures will widely extend the material choices and bring new opportunities to SOT devices in the future.
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38
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Sierra JF, Fabian J, Kawakami RK, Roche S, Valenzuela SO. Van der Waals heterostructures for spintronics and opto-spintronics. NATURE NANOTECHNOLOGY 2021; 16:856-868. [PMID: 34282312 DOI: 10.1038/s41565-021-00936-x] [Citation(s) in RCA: 116] [Impact Index Per Article: 38.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 06/03/2021] [Indexed: 06/13/2023]
Abstract
The large variety of 2D materials and their co-integration in van der Waals heterostructures enable innovative device engineering. In addition, their atomically thin nature promotes the design of artificial materials by proximity effects that originate from short-range interactions. Such a designer approach is particularly compelling for spintronics, which typically harnesses functionalities from thin layers of magnetic and non-magnetic materials and the interfaces between them. Here we provide an overview of recent progress in 2D spintronics and opto-spintronics using van der Waals heterostructures. After an introduction to the forefront of spin transport research, we highlight the unique spin-related phenomena arising from spin-orbit and magnetic proximity effects. We further describe the ability to create multifunctional hybrid heterostructures based on van der Waals materials, combining spin, valley and excitonic degrees of freedom. We end with an outlook on perspectives and challenges for the design and production of ultracompact all-2D spin devices and their potential applications in conventional and quantum technologies.
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Affiliation(s)
- Juan F Sierra
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain.
| | - Jaroslav Fabian
- Institute for Theoretical Physics, University of Regensburg, Regensburg, Germany
| | | | - Stephan Roche
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
| | - Sergio O Valenzuela
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain.
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain.
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39
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Chen X, Shi S, Shi G, Fan X, Song C, Zhou X, Bai H, Liao L, Zhou Y, Zhang H, Li A, Chen Y, Han X, Jiang S, Zhu Z, Wu H, Wang X, Xue D, Yang H, Pan F. Observation of the antiferromagnetic spin Hall effect. NATURE MATERIALS 2021; 20:800-804. [PMID: 33633354 DOI: 10.1038/s41563-021-00946-z] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 01/26/2021] [Indexed: 06/12/2023]
Abstract
The discovery of the spin Hall effect1 enabled the efficient generation and manipulation of the spin current. More recently, the magnetic spin Hall effect2,3 was observed in non-collinear antiferromagnets, where the spin conservation is broken due to the non-collinear spin configuration. This provides a unique opportunity to control the spin current and relevant device performance with controllable magnetization. Here, we report a magnetic spin Hall effect in a collinear antiferromagnet, Mn2Au. The spin currents are generated at two spin sublattices with broken spatial symmetry, and the antiparallel antiferromagnetic moments play an important role. Therefore, we term this effect the 'antiferromagnetic spin Hall effect'. The out-of-plane spins from the antiferromagnetic spin Hall effect are favourable for the efficient switching of perpendicular magnetized devices, which is required for high-density applications. The antiferromagnetic spin Hall effect adds another twist to the atomic-level control of spin currents via the antiferromagnetic spin structure.
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Affiliation(s)
- Xianzhe Chen
- MOE Key Laboratory of Advanced Materials, School of Materials Science and Engineering, Beijing Innovation Center for Future Chips, Tsinghua University, Beijing, China
| | - Shuyuan Shi
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Guoyi Shi
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, Singapore
| | - Xiaolong Fan
- The Key Lab for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou, China
| | - Cheng Song
- MOE Key Laboratory of Advanced Materials, School of Materials Science and Engineering, Beijing Innovation Center for Future Chips, Tsinghua University, Beijing, China.
| | - Xiaofeng Zhou
- MOE Key Laboratory of Advanced Materials, School of Materials Science and Engineering, Beijing Innovation Center for Future Chips, Tsinghua University, Beijing, China
| | - Hua Bai
- MOE Key Laboratory of Advanced Materials, School of Materials Science and Engineering, Beijing Innovation Center for Future Chips, Tsinghua University, Beijing, China
| | - Liyang Liao
- MOE Key Laboratory of Advanced Materials, School of Materials Science and Engineering, Beijing Innovation Center for Future Chips, Tsinghua University, Beijing, China
| | - Yongjian Zhou
- MOE Key Laboratory of Advanced Materials, School of Materials Science and Engineering, Beijing Innovation Center for Future Chips, Tsinghua University, Beijing, China
| | - Hanwen Zhang
- The Key Lab for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou, China
| | - Ang Li
- Beijing Key Lab of Microstructure and Property of Solids, Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing, China
| | - Yanhui Chen
- Beijing Key Lab of Microstructure and Property of Solids, Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing, China
| | - Xiaodong Han
- Beijing Key Lab of Microstructure and Property of Solids, Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing, China
| | - Shan Jiang
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan, China
| | - Zengwei Zhu
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan, China
| | - Huaqiang Wu
- Institute of Microelectronics, Tsinghua University, Beijing, China
| | - Xiangrong Wang
- Physics Department, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Desheng Xue
- The Key Lab for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou, China
| | - Hyunsoo Yang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore.
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, Singapore.
| | - Feng Pan
- MOE Key Laboratory of Advanced Materials, School of Materials Science and Engineering, Beijing Innovation Center for Future Chips, Tsinghua University, Beijing, China.
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Ding J, Liu C, Kalappattil V, Zhang Y, Mosendz O, Erugu U, Yu R, Tian J, DeMann A, Field SB, Yang X, Ding H, Tang J, Terris B, Fert A, Chen H, Wu M. Switching of a Magnet by Spin-Orbit Torque from a Topological Dirac Semimetal. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2005909. [PMID: 33938060 DOI: 10.1002/adma.202005909] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Indexed: 06/12/2023]
Abstract
Recent experiments show that topological surface states (TSS) in topological insulators (TI) can be exploited to manipulate magnetic ordering in ferromagnets. In principle, TSS should also exist for other topological materials, but it remains unexplored as to whether such states can also be utilized to manipulate ferromagnets. Herein, current-induced magnetization switching enabled by TSS in a non-TI topological material, namely, a topological Dirac semimetal α-Sn, is reported. The experiments use an α-Sn/Ag/CoFeB trilayer structure. The magnetization in the CoFeB layer can be switched by a charge current at room temperature, without an external magnetic field. The data show that the switching is driven by the TSS of the α-Sn layer, rather than spin-orbit coupling in the bulk of the α-Sn layer or current-produced heating. The switching efficiency is as high as in TI systems. This shows that the topological Dirac semimetal α-Sn is as promising as TI materials in terms of spintronic applications.
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Affiliation(s)
- Jinjun Ding
- Department of Physics, Colorado State University, Fort Collins, CO, 80523, USA
| | - Chuanpu Liu
- Department of Physics, Colorado State University, Fort Collins, CO, 80523, USA
| | | | - Yuejie Zhang
- Department of Physics, Colorado State University, Fort Collins, CO, 80523, USA
- School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China
| | - Oleksandr Mosendz
- Western Digital Research Center, Western Digital Corporation, San Jose, CA, 95119, USA
| | - Uppalaiah Erugu
- Department of Physics and Astronomy, University of Wyoming, Laramie, WY, 82071, USA
| | - Rui Yu
- Department of Physics, Colorado State University, Fort Collins, CO, 80523, USA
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, Jiangsu, 210093, China
| | - Jifa Tian
- Department of Physics and Astronomy, University of Wyoming, Laramie, WY, 82071, USA
| | - August DeMann
- Department of Physics, Colorado State University, Fort Collins, CO, 80523, USA
| | - Stuart B Field
- Department of Physics, Colorado State University, Fort Collins, CO, 80523, USA
| | - Xiaofei Yang
- School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China
| | - Haifeng Ding
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, Jiangsu, 210093, China
| | - Jinke Tang
- Department of Physics and Astronomy, University of Wyoming, Laramie, WY, 82071, USA
| | - Bruce Terris
- Western Digital Research Center, Western Digital Corporation, San Jose, CA, 95119, USA
| | - Albert Fert
- Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, Palaiseau, 91767, France
| | - Hua Chen
- Department of Physics, Colorado State University, Fort Collins, CO, 80523, USA
- School of Advanced Materials Discovery, Colorado State University, Fort Collins, CO, 80523, USA
| | - Mingzhong Wu
- Department of Physics, Colorado State University, Fort Collins, CO, 80523, USA
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41
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Ren L, Liu L, Shu X, Lin W, Yang P, Chen J, Teo KL. Spin-Orbit Torque Switching of a High-Quality Perpendicularly Magnetized Ferrimagnetic Heusler Mn 3Ge Film. ACS APPLIED MATERIALS & INTERFACES 2021; 13:18294-18300. [PMID: 33822573 DOI: 10.1021/acsami.1c01720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Current-induced spin-orbit torque (SOT) switching of magnetization has attracted great interest due to its potential application in magnetic memory devices, which offer low-energy consumption and high-speed writing. However, most of the SOT studies on perpendicularly magnetized anisotropy (PMA) magnets have been limited to heterostructures with interfacial PMA and poor thermal stability. Here, we experimentally demonstrate a SOT magnetization switching for a ferrimagnetic D022-Mn3Ge film with high bulk PMA and robust thermal stability factor under a critical current density of 6.6 × 1011 A m-2 through the spin Hall effect of an adjacent capping Pt and a buffer Cr layer. A large effective damping-like SOT efficiency of 2.37 mT/1010 A m-2 is determined using harmonic measurements in the structure. The effect of the double-spin source layers and the negative-exchange interaction of the ferrimagnet may explain the large SOT efficiency and the manifested magnetization switching of Mn3Ge. Our findings demonstrate that D022-Mn3Ge is a promising candidate for application in high-density SOT magnetic random-access memory devices.
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Affiliation(s)
- Lizhu Ren
- Department of Electrical and Computer Engineering, National University of Singapore, 117576, Singapore
| | - Liang Liu
- Department of Materials Science and Engineering, National University of Singapore, 117575, Singapore
| | - Xinyu Shu
- Department of Materials Science and Engineering, National University of Singapore, 117575, Singapore
| | - Weinan Lin
- Department of Materials Science and Engineering, National University of Singapore, 117575, Singapore
| | - Ping Yang
- Singapore Synchrotron Light Source (SSLS), National University of Singapore, 117603, Singapore
| | - Jingsheng Chen
- Department of Materials Science and Engineering, National University of Singapore, 117575, Singapore
| | - Kie Leong Teo
- Department of Electrical and Computer Engineering, National University of Singapore, 117576, Singapore
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42
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Peng CW, Liao WB, Chen TY, Pai CF. Efficient Spin-Orbit Torque Generation in Semiconducting WTe 2 with Hopping Transport. ACS APPLIED MATERIALS & INTERFACES 2021; 13:15950-15957. [PMID: 33769782 DOI: 10.1021/acsami.1c03530] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Spin-orbit torques (SOTs) from transition metal dichalcogenide systems (TMDs) in conjunction with ferromagnetic materials are recently found to be attractive in spintronics for their versatile features. However, most of the previously studied crystalline TMDs are prepared by mechanical exfoliation, which limits their potentials for industrial applications. Here, we show that amorphous WTe2 heterostructures deposited by magnetron sputtering possess a sizable damping-like SOT efficiency of ξDLWTe2 ≈ 0.20 and low damping constant of α = 0.009 ± 0.001. Only an extremely low critical switching current density of Jc≈ 7.05 × 109 A/m2 is required to achieve SOT-driven magnetization switching. The SOT efficiency is further proved to depend on the W and Te relative compositions in the co-sputtered W100-xTex samples, from which a sign change of ξDLWTe2 is observed. In addition, the electronic transport in amorphous WTe2 is found to be semiconducting and is governed by a hopping mechanism. With the above advantages and rich tunability, amorphous and semiconducting WTe2 serves as a unique SOT source for future spintronics applications.
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Affiliation(s)
- Cheng-Wei Peng
- Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Wei-Bang Liao
- Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Tian-Yue Chen
- Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Chi-Feng Pai
- Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan
- Center of Atomic Initiative for New Materials, National Taiwan University, Taipei 10617, Taiwan
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43
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Shao Q, Li P, Liu L, Yang H, Fukami S, Razavi A, Wu H, Wang K, Freimuth F, Mokrousov Y, Stiles MD, Emori S, Hoffmann A, Åkerman J, Roy K, Wang JP, Yang SH, Garello K, Zhang W. Roadmap of spin-orbit torques. IEEE TRANSACTIONS ON MAGNETICS 2021; 57:10.48550/arXiv.2104.11459. [PMID: 37057056 PMCID: PMC10091395 DOI: 10.48550/arxiv.2104.11459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Spin-orbit torque (SOT) is an emerging technology that enables the efficient manipulation of spintronic devices. The initial processes of interest in SOTs involved electric fields, spin-orbit coupling, conduction electron spins and magnetization. More recently interest has grown to include a variety of other processes that include phonons, magnons, or heat. Over the past decade, many materials have been explored to achieve a larger SOT efficiency. Recently, holistic design to maximize the performance of SOT devices has extended material research from a nonmagnetic layer to a magnetic layer. The rapid development of SOT has spurred a variety of SOT-based applications. In this Roadmap paper, we first review the theories of SOTs by introducing the various mechanisms thought to generate or control SOTs, such as the spin Hall effect, the Rashba-Edelstein effect, the orbital Hall effect, thermal gradients, magnons, and strain effects. Then, we discuss the materials that enable these effects, including metals, metallic alloys, topological insulators, two-dimensional materials, and complex oxides. We also discuss the important roles in SOT devices of different types of magnetic layers, such as magnetic insulators, antiferromagnets, and ferrimagnets. Afterward, we discuss device applications utilizing SOTs. We discuss and compare three-terminal and two-terminal SOT-magnetoresistive random-access memories (MRAMs); we mention various schemes to eliminate the need for an external field. We provide technological application considerations for SOT-MRAM and give perspectives on SOT-based neuromorphic devices and circuits. In addition to SOT-MRAM, we present SOT-based spintronic terahertz generators, nano-oscillators, and domain wall and skyrmion racetrack memories. This paper aims to achieve a comprehensive review of SOT theory, materials, and applications, guiding future SOT development in both the academic and industrial sectors.
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Affiliation(s)
- Qiming Shao
- Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology
| | - Peng Li
- Department of Electrical and Computer Engineering, Auburn University
| | - Luqiao Liu
- Electrical Engineering and Computer Science, Massachusetts Institute of Technology
| | - Hyunsoo Yang
- Department of Electrical and Computer Engineering, National University of Singapore
| | - Shunsuke Fukami
- Research Institute of Electrical Communication, Tohoku University
| | - Armin Razavi
- Department of Electrical and Computer Engineering, University of California, Los Angeles
| | - Hao Wu
- Department of Electrical and Computer Engineering, University of California, Los Angeles
| | - Kang Wang
- Department of Electrical and Computer Engineering, University of California, Los Angeles
| | | | | | - Mark D Stiles
- Alternative Computing Group, National Institute of Standards and Technology
| | | | - Axel Hoffmann
- Department of Materials Science and Engineering, University of Illinois Urbana-Champaign
| | | | - Kaushik Roy
- Department of Electrical and Computer Engineering, Purdue University
| | - Jian-Ping Wang
- Electrical and Computer Engineering Department, University of Minnesota
| | | | - Kevin Garello
- IMEC, Leuven, Belgium; CEA-Spintec, Grenoble, France
| | - Wei Zhang
- Physics Department, Oakland University
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44
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Schröter NBM, Robredo I, Klemenz S, Kirby RJ, Krieger JA, Pei D, Yu T, Stolz S, Schmitt T, Dudin P, Kim TK, Cacho C, Schnyder A, Bergara A, Strocov VN, de Juan F, Vergniory MG, Schoop LM. Weyl fermions, Fermi arcs, and minority-spin carriers in ferromagnetic CoS 2. SCIENCE ADVANCES 2020; 6:eabd5000. [PMID: 33355138 PMCID: PMC11206217 DOI: 10.1126/sciadv.abd5000] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 11/05/2020] [Indexed: 06/12/2023]
Abstract
Magnetic Weyl semimetals are a newly discovered class of topological materials that may serve as a platform for exotic phenomena, such as axion insulators or the quantum anomalous Hall effect. Here, we use angle-resolved photoelectron spectroscopy and ab initio calculations to discover Weyl cones in CoS2, a ferromagnet with pyrite structure that has been long studied as a candidate for half-metallicity, which makes it an attractive material for spintronic devices. We directly observe the topological Fermi arc surface states that link the Weyl nodes, which will influence the performance of CoS2 as a spin injector by modifying its spin polarization at interfaces. In addition, we directly observe a minority-spin bulk electron pocket in the corner of the Brillouin zone, which proves that CoS2 cannot be a true half-metal.
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Affiliation(s)
- Niels B M Schröter
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland.
| | - Iñigo Robredo
- Donostia International Physics Center, 20018 Donostia-San Sebastian, Spain
- Condensed Matter Physics Department, University of the Basque Country UPV/EHU, 48080 Bilbao, Spain
| | - Sebastian Klemenz
- Department of Chemistry, Princeton University, Princeton, NJ 08540, USA
| | - Robert J Kirby
- Department of Chemistry, Princeton University, Princeton, NJ 08540, USA
| | - Jonas A Krieger
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
- Laboratorium für Festkörperphysik, ETH Zurich, CH-8093 Zurich, Switzerland
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - Ding Pei
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
| | - Tianlun Yu
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
- Advanced Materials Laboratory, State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Samuel Stolz
- EMPA, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland
- Institute of Condensed Matter Physics, Station 3, EPFL, 1015 Lausanne, Switzerland
| | - Thorsten Schmitt
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | | | | | | | - Andreas Schnyder
- Max Planck Institute for Solid State Research, 70569, Stuttgart, Germany
| | - Aitor Bergara
- Donostia International Physics Center, 20018 Donostia-San Sebastian, Spain
- Condensed Matter Physics Department, University of the Basque Country UPV/EHU, 48080 Bilbao, Spain
- Centro de Física de Materiales, Centro Mixto CSIC -UPV/EHU, 20018 Donostia, Spain
| | - Vladimir N Strocov
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - Fernando de Juan
- Donostia International Physics Center, 20018 Donostia-San Sebastian, Spain
- IKERBASQUE, Basque Foundation for Science, Maria Diaz de Haro 3, 48013 Bilbao, Spain
| | - Maia G Vergniory
- Donostia International Physics Center, 20018 Donostia-San Sebastian, Spain.
- IKERBASQUE, Basque Foundation for Science, Maria Diaz de Haro 3, 48013 Bilbao, Spain
| | - Leslie M Schoop
- Department of Chemistry, Princeton University, Princeton, NJ 08540, USA.
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Hwang J, Lee S, Lee JE, Kang M, Ryu H, Joo HJ, Denlinger J, Park JH, Hwang C. Tunable Kondo Resonance at a Pristine Two-Dimensional Dirac Semimetal on a Kondo Insulator. NANO LETTERS 2020; 20:7973-7979. [PMID: 33104350 DOI: 10.1021/acs.nanolett.0c02751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The proximity of two different materials leads to an intricate coupling of quasiparticles so that an unprecedented electronic state is often realized at the interface. Here, we demonstrate a resonance-type many-body ground state in graphene, a nonmagnetic two-dimensional Dirac semimetal, when grown on SmB6, a Kondo insulator, via thermal decomposition of fullerene molecules. This ground state is typically observed in three-dimensional magnetic materials with correlated electrons. Above the characteristic Kondo temperature of the substrate, the electron band structure of pristine graphene remains almost intact. As temperature decreases, however, the Dirac Fermions of graphene become hybridized with the Sm 4f states. Remarkable enhancement of the hybridization and Kondo resonance is observed with further cooling and increasing charge-carrier density of graphene, evidencing the Kondo screening of the Sm 4f local magnetic moment by the conduction electrons of graphene at the interface. These findings manifest the realization of the Kondo effect in graphene by the proximity of SmB6 that is tuned by the temperature and charge-carrier density of graphene.
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Affiliation(s)
- Jinwoong Hwang
- Department of Physics, Pusan National University, Busan 46241, South Korea
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Seungseok Lee
- Center for Complex Phase Materials, Max Planck POSTECH/Korea Research Initiative, Pohang 37673, South Korea
- Division of Advanced Material Science, Pohang University of Science and Technology, Pohang 37673, South Korea
| | - Ji-Eun Lee
- Department of Physics, Pusan National University, Busan 46241, South Korea
- Center for Spintronics, Korea Institute of Science and Technology, Seoul 02792, South Korea
| | - Minhee Kang
- Department of Physics, Pusan National University, Busan 46241, South Korea
| | - Hyejin Ryu
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Center for Complex Phase Materials, Max Planck POSTECH/Korea Research Initiative, Pohang 37673, South Korea
- Center for Spintronics, Korea Institute of Science and Technology, Seoul 02792, South Korea
| | - Hyun-Jeong Joo
- Department of Physics, Pusan National University, Busan 46241, South Korea
| | - Jonathan Denlinger
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Jae-Hoon Park
- Center for Complex Phase Materials, Max Planck POSTECH/Korea Research Initiative, Pohang 37673, South Korea
- Division of Advanced Material Science, Pohang University of Science and Technology, Pohang 37673, South Korea
- Department of Physics, Pohang University of Science and Technology, Pohang 37673, South Korea
| | - Choongyu Hwang
- Department of Physics, Pusan National University, Busan 46241, South Korea
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Kim JM, Kim DJ, Cheon CY, Moon KW, Kim C, Cao Van P, Jeong JR, Hwang C, Lee KJ, Park BG. Observation of Thermal Spin-Orbit Torque in W/CoFeB/MgO Structures. NANO LETTERS 2020; 20:7803-7810. [PMID: 33054243 DOI: 10.1021/acs.nanolett.0c01702] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Coupling of spin and heat currents enables the spin Nernst effect, the thermal generation of spin currents in nonmagnets that have strong spin-orbit interaction. Analogous to the spin Hall effect that electrically generates spin currents and associated electrical spin-orbit torques (SOTs), the spin Nernst effect can exert thermal SOTs on an adjacent magnetic layer and control the magnetization direction. Here, the thermal SOT caused by the spin Nernst effect is experimentally demonstrated in W/CoFeB/MgO structures. It is found that an in-plane temperature gradient across the sample generates a magnetic torque and modulates the switching field of the perpendicularly magnetized CoFeB. The W thickness dependence suggests that the torque originates mainly from thermal spin currents induced in W. Moreover, the thermal SOT reduces the critical current for SOT-induced magnetization switching, demonstrating that it can be utilized to control the magnetization in spintronic devices.
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Affiliation(s)
- Jeong-Mok Kim
- Department of Materials Science and Engineering, KAIST 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
| | - Dong-Jun Kim
- Department of Materials Science and Engineering, KAIST 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
| | - Cheol-Yeon Cheon
- Department of Materials Science and Engineering, KAIST 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
| | - Kyoung-Woong Moon
- Center for Nanometrology, Korea Research Institute of Standards and Science 267 Gajung-ro, Yuseong-gu, Daejeon, Korea, 34113, Republic of Korea
| | - Changsoo Kim
- Center for Nanometrology, Korea Research Institute of Standards and Science 267 Gajung-ro, Yuseong-gu, Daejeon, Korea, 34113, Republic of Korea
| | - Phuoc Cao Van
- Department of Materials Science and Engineering, Graduate School of Energy Science and Technology, Chungnam National University, Daejeon, 34134, Republic of Korea
| | - Jong-Ryul Jeong
- Department of Materials Science and Engineering, Graduate School of Energy Science and Technology, Chungnam National University, Daejeon, 34134, Republic of Korea
| | - Chanyong Hwang
- Center for Nanometrology, Korea Research Institute of Standards and Science 267 Gajung-ro, Yuseong-gu, Daejeon, Korea, 34113, Republic of Korea
| | - Kyung-Jin Lee
- Department of Materials Science and Engineering, Korea University KU-KIST Graduate School of Converging Science and Technology, Korea University 145 Anam-ro, Anam-dong, Seongbuk-gu, Seoul, Korea, 02841, Republic of Korea
- Department of Physics, KAIST 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
| | - Byong-Guk Park
- Department of Materials Science and Engineering, KAIST 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
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Amin VP, Haney PM, Stiles MD. Interfacial spin-orbit torques. JOURNAL OF APPLIED PHYSICS 2020; 128:10.1063/5.0024019. [PMID: 34121763 PMCID: PMC8194107 DOI: 10.1063/5.0024019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 09/30/2020] [Indexed: 06/12/2023]
Abstract
Spin-orbit torques offer a promising mechanism for electrically controlling magnetization dynamics in nanoscale heterostructures. While spin-orbit torques occur predominately at interfaces, the physical mechanisms underlying these torques can originate in both the bulk layers and at interfaces. Classifying spin-orbit torques based on the region that they originate in provides clues as to how to optimize the effect. While most bulk spin-orbit torque contributions are well studied, many of the interfacial contributions allowed by symmetry have yet to be fully explored theoretically and experimentally. To facilitate progress, we review interfacial spin-orbit torques from a semiclassical viewpoint and relate these contributions to recent experimental results. Within the same model, we show the relationship between different interface transport parameters. For charges and spins flowing perpendicular to the interface, interfacial spin-orbit coupling both modifies the mixing conductance of magnetoelectronic circuit theory and gives rise to spin memory loss. For in-plane electric fields, interfacial spin-orbit coupling gives rise to torques described by spin-orbit filtering, spin swapping and precession. In addition, these same interfacial processes generate spin currents that flow into the non-magnetic layer. For in-plane electric fields in trilayer structures, the spin currents generated at the interface between one ferromagnetic layer and the non-magnetic spacer layer can propagate through the non-magnetic layer to produce novel torques on the other ferromagnetic layer.
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Affiliation(s)
- V. P. Amin
- Department of Chemistry & Biochemistry, University of Maryland, College Park, MD 20742, USA
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - P. M. Haney
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - M. D. Stiles
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
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48
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Gupta V, Cham TM, Stiehl GM, Bose A, Mittelstaedt JA, Kang K, Jiang S, Mak KF, Shan J, Buhrman RA, Ralph DC. Manipulation of the van der Waals Magnet Cr 2Ge 2Te 6 by Spin-Orbit Torques. NANO LETTERS 2020; 20:7482-7488. [PMID: 32975955 DOI: 10.1021/acs.nanolett.0c02965] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We report measurements of current-induced thermoelectric and spin-orbit torque effects within devices in which multilayers of the semiconducting two-dimensional van der Waals magnet Cr2Ge2Te6 (CGT) are integrated with Pt and Ta metal overlayers. We show that the magnetic orientation of the CGT can be detected accurately either electrically (using an anomalous Hall effect) or optically (using magnetic circular dichroism) with good consistency. The samples exhibit large thermoelectric effects, but nevertheless, the spin-orbit torque can be measured quantitatively using the angle-dependent second harmonic Hall technique. For CGT/Pt, we measure the spin-orbit torque efficiency to be similar to conventional metallic-ferromagnet/Pt devices with the same Pt resistivity. The interfacial transparency for spin currents is therefore similar in both classes of devices. Our results demonstrate the promise of incorporating semiconducting 2D magnets within spin-orbitronic and magneto-thermal devices.
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Affiliation(s)
- Vishakha Gupta
- Cornell University, Ithaca, New York 14850, United States
| | - Thow Min Cham
- Cornell University, Ithaca, New York 14850, United States
| | | | - Arnab Bose
- Cornell University, Ithaca, New York 14850, United States
| | | | - Kaifei Kang
- Cornell University, Ithaca, New York 14850, United States
| | - Shengwei Jiang
- Cornell University, Ithaca, New York 14850, United States
| | - Kin Fai Mak
- Cornell University, Ithaca, New York 14850, United States
| | - Jie Shan
- Cornell University, Ithaca, New York 14850, United States
| | | | - Daniel C Ralph
- Cornell University, Ithaca, New York 14850, United States
- Kavli Institute at Cornell, Ithaca, New York 14853, United States
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Broadway DA, Scholten SC, Tan C, Dontschuk N, Lillie SE, Johnson BC, Zheng G, Wang Z, Oganov AR, Tian S, Li C, Lei H, Wang L, Hollenberg LCL, Tetienne JP. Imaging Domain Reversal in an Ultrathin Van der Waals Ferromagnet. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e2003314. [PMID: 32830379 DOI: 10.1002/adma.202003314] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 06/24/2020] [Accepted: 07/01/2020] [Indexed: 06/11/2023]
Abstract
The recent isolation of 2D van der Waals magnetic materials has uncovered rich physics that often differs from the magnetic behavior of their bulk counterparts. However, the microscopic details of fundamental processes such as the initial magnetization or domain reversal, which govern the magnetic hysteresis, remain largely unknown in the ultrathin limit. Here a widefield nitrogen-vacancy (NV) microscope is employed to directly image these processes in few-layer flakes of the magnetic semiconductor vanadium triiodide (VI3 ). Complete and abrupt switching of most flakes is observed at fields Hc ≈ 0.5-1 T (at 5 K) independent of thickness. The coercive field decreases as the temperature approaches the Curie temperature (Tc ≈ 50 K); however, the switching remains abrupt. The initial magnetization process is then imaged, which reveals thickness-dependent domain wall depinning fields well below Hc . These results point to ultrathin VI3 being a nucleation-type hard ferromagnet, where the coercive field is set by the anisotropy-limited domain wall nucleation field. This work illustrates the power of widefield NV microscopy to investigate magnetization processes in van der Waals ferromagnets, which can be used to elucidate the origin of the hard ferromagnetic properties of other materials and explore field- and current-driven domain wall dynamics.
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Affiliation(s)
- David A Broadway
- School of Physics, University of Melbourne, Parkville, VIC 3010, Australia
- Centre for Quantum Computation and Communication Technology, School of Physics, University of Melbourne, Parkville, VIC 3010, Australia
- Department of Physics, University of Basel, Klingelbergstrasse 82, Basel, CH-4056, Switzerland
| | - Sam C Scholten
- School of Physics, University of Melbourne, Parkville, VIC 3010, Australia
- Centre for Quantum Computation and Communication Technology, School of Physics, University of Melbourne, Parkville, VIC 3010, Australia
| | - Cheng Tan
- School of Science, RMIT University, Melbourne, VIC 3000, Australia
| | - Nikolai Dontschuk
- School of Physics, University of Melbourne, Parkville, VIC 3010, Australia
- Centre for Quantum Computation and Communication Technology, School of Physics, University of Melbourne, Parkville, VIC 3010, Australia
| | - Scott E Lillie
- School of Physics, University of Melbourne, Parkville, VIC 3010, Australia
- Centre for Quantum Computation and Communication Technology, School of Physics, University of Melbourne, Parkville, VIC 3010, Australia
| | - Brett C Johnson
- School of Physics, University of Melbourne, Parkville, VIC 3010, Australia
- Centre for Quantum Computation and Communication Technology, School of Physics, University of Melbourne, Parkville, VIC 3010, Australia
| | - Guolin Zheng
- School of Science, RMIT University, Melbourne, VIC 3000, Australia
| | - Zhenhai Wang
- Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, 3 Nobel Street, Moscow, 143026, Russia
- School of Telecommunication and Information Engineering, Nanjing University of Posts and Telecommunications, Nanjing, Jiangsu, 210003, China
| | - Artem R Oganov
- Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, 3 Nobel Street, Moscow, 143026, Russia
- Moscow Institute of Physics and Technology, 9 Institutsky Lane, Dolgoprudny, Moscow Region, 141700, Russia
- International Center for Materials Discovery, Northwestern Polytechnical University, Xi'an, 710072, China
| | - Shangjie Tian
- Department of Physics and Beijing Key Laboratory of Optoelectronic Functional Materials and Micro-Nano Devices, Renmin University of China, Beijing, 100872, China
| | - Chenghe Li
- Department of Physics and Beijing Key Laboratory of Optoelectronic Functional Materials and Micro-Nano Devices, Renmin University of China, Beijing, 100872, China
| | - Hechang Lei
- Department of Physics and Beijing Key Laboratory of Optoelectronic Functional Materials and Micro-Nano Devices, Renmin University of China, Beijing, 100872, China
| | - Lan Wang
- School of Science, RMIT University, Melbourne, VIC 3000, Australia
| | - Lloyd C L Hollenberg
- School of Physics, University of Melbourne, Parkville, VIC 3010, Australia
- Centre for Quantum Computation and Communication Technology, School of Physics, University of Melbourne, Parkville, VIC 3010, Australia
| | - Jean-Philippe Tetienne
- School of Physics, University of Melbourne, Parkville, VIC 3010, Australia
- Centre for Quantum Computation and Communication Technology, School of Physics, University of Melbourne, Parkville, VIC 3010, Australia
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50
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Abstract
Science, engineering, and medicine ultimately demand fast information processing with ultra-low power consumption. The recently developed spin-orbit torque (SOT)-induced magnetization switching paradigm has been fueling opportunities for spin-orbitronic devices, i.e., enabling SOT memory and logic devices at sub-nano second and sub-picojoule regimes. Importantly, spin-orbitronic devices are intrinsic of nonvolatility, anti-radiation, unlimited endurance, excellent stability, and CMOS compatibility, toward emerging applications, e.g., processing in-memory, neuromorphic computing, probabilistic computing, and 3D magnetic random access memory. Nevertheless, the cutting-edge SOT-based devices and application remain at a premature stage owing to the lack of scalable methodology on the field-free SOT switching. Moreover, spin-orbitronics poises as an interdisciplinary field to be driven by goals of both fundamental discoveries and application innovations, to open fascinating new paths for basic research and new line of technologies. In this perspective, the specific challenges and opportunities are summarized to exert momentum on both research and eventual applications of spin-orbitronic devices.
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Affiliation(s)
- Yi Cao
- Beijing Academy of Quantum Information Sciences, Beijing 100193, P. R. China
| | - Guozhong Xing
- Key Laboratory of Microelectronic Devices & Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029, P. R. China
| | - Huai Lin
- Key Laboratory of Microelectronic Devices & Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029, P. R. China
| | - Nan Zhang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, P. R. China
| | - Houzhi Zheng
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, P. R. China
| | - Kaiyou Wang
- Beijing Academy of Quantum Information Sciences, Beijing 100193, P. R. China
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, P. R. China
- Corresponding author
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