1
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Kim DJ, Kim KW, Lee K, Oh JH, Chen X, Yang S, Pu Y, Liu Y, Hu F, Cao Van P, Jeong JR, Lee KJ, Yang H. Spin Hall-induced bilinear magnetoelectric resistance. NATURE MATERIALS 2024:10.1038/s41563-024-02000-0. [PMID: 39266677 DOI: 10.1038/s41563-024-02000-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Accepted: 08/15/2024] [Indexed: 09/14/2024]
Abstract
Magnetoresistance is a fundamental transport phenomenon that is essential for reading the magnetic states for various information storage, innovative computing and sensor devices. Recent studies have expanded the scope of magnetoresistances to the nonlinear regime, such as a bilinear magnetoelectric resistance (BMER), which is proportional to both electric field and magnetic field. Here we demonstrate that the BMER is a general phenomenon that arises even in three-dimensional systems without explicit momentum-space spin textures. Our theory suggests that the spin Hall effect enables the BMER provided that the magnitudes of spin accumulation at the top and bottom interfaces are not identical. The sign of the BMER follows the sign of the spin Hall effect of heavy metals, thereby evidencing that the BMER originates from the bulk spin Hall effect. Our observation suggests that the BMER serves as a general nonlinear transport characteristic in three-dimensional systems, especially playing a crucial role in antiferromagnetic spintronics.
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Affiliation(s)
- Dong-Jun Kim
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Kyoung-Whan Kim
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, Republic of Korea
- Department of Physics, Yonsei University, Seoul, Republic of Korea
| | - Kyusup Lee
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
- Department of Physics, Pukyong National University, Busan, Republic of Korea
| | - Jung Hyun Oh
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Xinhou Chen
- 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
| | - Yuchen Pu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Yakun Liu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Fanrui Hu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Phuoc Cao Van
- Department of Materials Science and Engineering, Chungnam National University, Daejeon, Republic of Korea
| | - Jong-Ryul Jeong
- Department of Materials Science and Engineering, Chungnam National University, Daejeon, Republic of Korea
| | - Kyung-Jin Lee
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Hyunsoo Yang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore.
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2
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Watanabe H, Yanase Y. Magnetic parity violation and parity-time-reversal-symmetric magnets. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:373001. [PMID: 38899401 DOI: 10.1088/1361-648x/ad52dd] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Accepted: 05/31/2024] [Indexed: 06/21/2024]
Abstract
Parity-time-reversal symmetry (PTsymmetry), a symmetry for the combined operations of space inversion (P) and time reversal (T), is a fundamental concept of physics and characterizes the functionality of materials as well asPandTsymmetries. In particular, thePT-symmetric systems can be found in the centrosymmetric crystals undergoing the parity-violating magnetic order which we call the odd-parity magnetic multipole order. While this spontaneous order leavesPTsymmetry intact, the simultaneous violation ofPandTsymmetries gives rise to various emergent responses that are qualitatively different from those allowed by the nonmagneticP-symmetry breaking or by the ferromagnetic order. In this review, we introduce candidates hosting the intriguing spontaneous order and overview the characteristic physical responses. Various off-diagonal and/or nonreciprocal responses are identified, which are closely related to the unusual electronic structures such as hidden spin-momentum locking and asymmetric band dispersion.
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Affiliation(s)
- Hikaru Watanabe
- Research Center for Advanced Science and Technology, University of Tokyo, Meguro-ku, Tokyo 153-8904, Japan
| | - Youichi Yanase
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
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3
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Shi J, Arpaci S, Lopez-Dominguez V, Sangwan VK, Mahfouzi F, Kim J, Athas JG, Hamdi M, Aygen C, Arava H, Phatak C, Carpentieri M, Jiang JS, Grayson MA, Kioussis N, Finocchio G, Hersam MC, Khalili Amiri P. Electrically Controlled All-Antiferromagnetic Tunnel Junctions on Silicon with Large Room-Temperature Magnetoresistance. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2312008. [PMID: 38501999 DOI: 10.1002/adma.202312008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2023] [Revised: 02/11/2024] [Indexed: 03/20/2024]
Abstract
Antiferromagnetic (AFM) materials are a pathway to spintronic memory and computing devices with unprecedented speed, energy efficiency, and bit density. Realizing this potential requires AFM devices with simultaneous electrical writing and reading of information, which are also compatible with established silicon-based manufacturing. Recent experiments have shown tunneling magnetoresistance (TMR) readout in epitaxial AFM tunnel junctions. However, these TMR structures are not grown using a silicon-compatible deposition process, and controlling their AFM order required external magnetic fields. Here are shown three-terminal AFM tunnel junctions based on the noncollinear antiferromagnet PtMn3, sputter-deposited on silicon. The devices simultaneously exhibit electrical switching using electric currents, and electrical readout by a large room-temperature TMR effect. First-principles calculations explain the TMR in terms of the momentum-resolved spin-dependent tunneling conduction in tunnel junctions with noncollinear AFM electrodes.
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Affiliation(s)
- Jiacheng Shi
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Sevdenur Arpaci
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, 60208, USA
- Applied Physics Program, Northwestern University, Evanston, IL, 60208, USA
| | - Victor Lopez-Dominguez
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, 60208, USA
- Institute of Advanced Materials (INAM), Universitat Jaume I, Castellón, 12006, Spain
| | - Vinod K Sangwan
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Farzad Mahfouzi
- Department of Physics and Astronomy, California State University Northridge, Northridge, CA, 91330, USA
| | - Jinwoong Kim
- Department of Physics and Astronomy, California State University Northridge, Northridge, CA, 91330, USA
| | - Jordan G Athas
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Mohammad Hamdi
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Can Aygen
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Hanu Arava
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Charudatta Phatak
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Mario Carpentieri
- Department of Electrical and Information Engineering, Politecnico di Bari, Bari, 70125, Italy
| | - Jidong S Jiang
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Matthew A Grayson
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, 60208, USA
- Applied Physics Program, Northwestern University, Evanston, IL, 60208, USA
| | - Nicholas Kioussis
- Department of Physics and Astronomy, California State University Northridge, Northridge, CA, 91330, USA
| | - Giovanni Finocchio
- Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, Messina, 98166, Italy
| | - Mark C Hersam
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, 60208, USA
- Applied Physics Program, Northwestern University, Evanston, IL, 60208, USA
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
- Department of Chemistry, Northwestern University, Evanston, IL, 60208, USA
| | - Pedram Khalili Amiri
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, 60208, USA
- Applied Physics Program, Northwestern University, Evanston, IL, 60208, USA
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4
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Chen H, Liu L, Zhou X, Meng Z, Wang X, Duan Z, Zhao G, Yan H, Qin P, Liu Z. Emerging Antiferromagnets for Spintronics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2310379. [PMID: 38183310 DOI: 10.1002/adma.202310379] [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: 12/18/2023] [Indexed: 01/08/2024]
Abstract
Antiferromagnets constitute promising contender materials for next-generation spintronic devices with superior stability, scalability, and dynamics. Nevertheless, the perception of well-established ferromagnetic spintronics underpinned by spontaneous magnetization seemed to indicate the inadequacy of antiferromagnets for spintronics-their compensated magnetization has been perceived to result in uncontrollable antiferromagnetic order and subtle magnetoelectronic responses. However, remarkable advancements have been achieved in antiferromagnetic spintronics in recent years, with consecutive unanticipated discoveries substantiating the feasibility of antiferromagnet-centered spintronic devices. It is emphasized that, distinct from ferromagnets, the richness in complex antiferromagnetic crystal structures is the unique and essential virtue of antiferromagnets that can open up their endless possibilities of novel phenomena and functionality for spintronics. In this Perspective, the recent progress in antiferromagnetic spintronics is reviewed, with a particular focus on that based on several kinds of antiferromagnets with special antiferromagnetic crystal structures. The latest developments in efficiently manipulating antiferromagnetic order, exploring novel antiferromagnetic physical responses, and demonstrating prototype antiferromagnetic spintronic devices are discussed. An outlook on future research directions is also provided. It is hoped that this Perspective can serve as guidance for readers who are interested in this field and encourage unprecedented studies on antiferromagnetic spintronic materials, phenomena, and devices.
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Affiliation(s)
- Hongyu Chen
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Li Liu
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Xiaorong Zhou
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Ziang Meng
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Xiaoning Wang
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Zhiyuan Duan
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Guojian Zhao
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Han Yan
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Peixin Qin
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Zhiqi Liu
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
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5
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Schmitt C, Rajan A, Beneke G, Kumar A, Sparmann T, Meer H, Bednarz B, Ramos R, Niño MA, Foerster M, Saitoh E, Kläui M. Mechanisms of Electrical Switching of Ultrathin CoO/Pt Bilayers. NANO LETTERS 2024; 24:1471-1476. [PMID: 38216142 PMCID: PMC10853954 DOI: 10.1021/acs.nanolett.3c02890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 12/21/2023] [Accepted: 12/21/2023] [Indexed: 01/14/2024]
Abstract
We study current-induced switching of the Néel vector in CoO/Pt bilayers to understand the underlying antiferromagnetic switching mechanism. Surprisingly, we find that for ultrathin CoO/Pt bilayers electrical pulses along the same path can lead to an increase or decrease of the spin Hall magnetoresistance signal, depending on the current density of the pulse. By comparing these results to XMLD-PEEM imaging of the antiferromagnetic domain structure before and after the application of current pulses, we reveal the details of the reorientation of the Néel vector in ultrathin CoO(4 nm). This allows us to understand how opposite resistance changes can result from a thermomagnetoelastic switching mechanism. Importantly, our spatially resolved imaging shows that regions where the current pulses are applied and regions further away exhibit different switched spin structures, which can be explained by a spin-orbit torque-based switching mechanism that can dominate in very thin films.
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Affiliation(s)
- Christin Schmitt
- Institute
of Physics, Johannes Gutenberg University
Mainz, 55099 Mainz, Germany
| | - Adithya Rajan
- Institute
of Physics, Johannes Gutenberg University
Mainz, 55099 Mainz, Germany
| | - Grischa Beneke
- Institute
of Physics, Johannes Gutenberg University
Mainz, 55099 Mainz, Germany
| | - Aditya Kumar
- Institute
of Physics, Johannes Gutenberg University
Mainz, 55099 Mainz, Germany
| | - Tobias Sparmann
- Institute
of Physics, Johannes Gutenberg University
Mainz, 55099 Mainz, Germany
| | - Hendrik Meer
- Institute
of Physics, Johannes Gutenberg University
Mainz, 55099 Mainz, Germany
| | - Beatrice Bednarz
- Institute
of Physics, Johannes Gutenberg University
Mainz, 55099 Mainz, Germany
| | - Rafael Ramos
- WPI-Advanced
Institute for Materials Research, Tohoku
University, Sendai 980-8577, Japan
| | - Miguel Angel Niño
- ALBA
Synchrotron Light Facility, 08290 Cerdanyola del Valles (Barcelona), Spain
| | - Michael Foerster
- ALBA
Synchrotron Light Facility, 08290 Cerdanyola del Valles (Barcelona), Spain
| | - Eiji Saitoh
- WPI-Advanced
Institute for Materials Research, Tohoku
University, Sendai 980-8577, Japan
- Institute
for Materials Research, Tohoku University, Sendai 980-8577, Japan
- The
Institute of AI and Beyond, The University
of Tokyo, Tokyo 113-8656, Japan
- Center
for
Spintronics Research Network, Tohoku University, Sendai 980-8577, Japan
- Department
of Applied Physics, The University of Tokyo, Tokyo 113-8656, Japan
| | - Mathias Kläui
- Institute
of Physics, Johannes Gutenberg University
Mainz, 55099 Mainz, Germany
- Graduate
School of Excellence Materials Science in Mainz, 55128 Mainz, Germany
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6
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Yoon JY, Zhang P, Chou CT, Takeuchi Y, Uchimura T, Hou JT, Han J, Kanai S, Ohno H, Fukami S, Liu L. Handedness anomaly in a non-collinear antiferromagnet under spin-orbit torque. NATURE MATERIALS 2023; 22:1106-1113. [PMID: 37537356 DOI: 10.1038/s41563-023-01620-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Accepted: 06/23/2023] [Indexed: 08/05/2023]
Abstract
Non-collinear antiferromagnets are an emerging family of spintronic materials because they not only possess the general advantages of antiferromagnets but also enable more advanced functionalities. Recently, in an intriguing non-collinear antiferromagnet Mn3Sn, where the octupole moment is defined as the collective magnetic order parameter, spin-orbit torque (SOT) switching has been achieved in seemingly the same protocol as in ferromagnets. Nevertheless, it is fundamentally important to explore the unknown octupole moment dynamics and contrast it with the magnetization vector of ferromagnets. Here we report a handedness anomaly in the SOT-driven dynamics of Mn3Sn: when spin current is injected, the octupole moment rotates in the opposite direction to the individual moments, leading to a SOT switching polarity distinct from ferromagnets. By using second-harmonic and d.c. magnetometry, we track the SOT effect onto the octupole moment during its rotation and reveal that the handedness anomaly stems from the interactions between the injected spin and the unique chiral-spin structure of Mn3Sn. We further establish the torque balancing equation of the magnetic octupole moment and quantify the SOT efficiency. Our finding provides a guideline for understanding and implementing the electrical manipulation of non-collinear antiferromagnets, which in nature differs from the well-established collinear magnets.
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Affiliation(s)
- Ju-Young Yoon
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai, Japan
- Graduate School of Engineering, Tohoku University, Sendai, Japan
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Pengxiang Zhang
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Chung-Tao Chou
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Yutaro Takeuchi
- WPI-Advanced Institute for Materials Research, Tohoku University, Sendai, Japan
| | - Tomohiro Uchimura
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai, Japan
- Graduate School of Engineering, Tohoku University, Sendai, Japan
| | - Justin T Hou
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Jiahao Han
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai, Japan.
| | - Shun Kanai
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai, Japan
- Graduate School of Engineering, Tohoku University, Sendai, Japan
- WPI-Advanced Institute for Materials Research, Tohoku University, Sendai, Japan
- Center for Science and Innovation in Spintronics, Tohoku University, Sendai, Japan
- Division for the Establishment of Frontier Sciences of Organization for Advanced Studies, Tohoku University, Sendai, Japan
| | - Hideo Ohno
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai, Japan
- Graduate School of Engineering, Tohoku University, Sendai, Japan
- WPI-Advanced Institute for Materials Research, Tohoku University, Sendai, Japan
- Center for Science and Innovation in Spintronics, Tohoku University, Sendai, Japan
- Center for Innovative Integrated Electronic Systems, Tohoku University, Sendai, Japan
| | - Shunsuke Fukami
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai, Japan.
- Graduate School of Engineering, Tohoku University, Sendai, Japan.
- WPI-Advanced Institute for Materials Research, Tohoku University, Sendai, Japan.
- Center for Science and Innovation in Spintronics, Tohoku University, Sendai, Japan.
- Center for Innovative Integrated Electronic Systems, Tohoku University, Sendai, Japan.
- Inamori Research Institute for Science, Kyoto, Japan.
| | - Luqiao Liu
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA.
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7
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Han J, Cheng R, Liu L, Ohno H, Fukami S. Coherent antiferromagnetic spintronics. NATURE MATERIALS 2023; 22:684-695. [PMID: 36941390 DOI: 10.1038/s41563-023-01492-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 01/25/2023] [Indexed: 06/03/2023]
Abstract
Antiferromagnets have attracted extensive interest as a material platform in spintronics. So far, antiferromagnet-enabled spin-orbitronics, spin-transfer electronics and spin caloritronics have formed the bases of antiferromagnetic spintronics. Spin transport and manipulation based on coherent antiferromagnetic dynamics have recently emerged, pushing the developing field of antiferromagnetic spintronics towards a new stage distinguished by the features of spin coherence. In this Review, we categorize and analyse the critical effects that harness the coherence of antiferromagnets for spintronic applications, including spin pumping from monochromatic antiferromagnetic magnons, spin transmission via phase-correlated antiferromagnetic magnons, electrically induced spin rotation and ultrafast spin-orbit effects in antiferromagnets. We also discuss future opportunities in research and applications stimulated by the principles, materials and phenomena of coherent antiferromagnetic spintronics.
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Affiliation(s)
- Jiahao Han
- Research Institute of Electrical Communication, Tohoku University, Sendai, Japan.
| | - 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
| | - Luqiao Liu
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Hideo Ohno
- Research Institute of Electrical Communication, Tohoku University, Sendai, Japan
- Center for Science and Innovation in Spintronics, Tohoku University, Sendai, Japan
- Center for Innovative Integrated Electronic Systems, Tohoku University, Sendai, Japan
- WPI-Advanced Institute for Materials Research, Tohoku University, Sendai, Japan
| | - Shunsuke Fukami
- Research Institute of Electrical Communication, Tohoku University, Sendai, Japan.
- Center for Science and Innovation in Spintronics, Tohoku University, Sendai, Japan.
- Center for Innovative Integrated Electronic Systems, Tohoku University, Sendai, Japan.
- WPI-Advanced Institute for Materials Research, Tohoku University, Sendai, Japan.
- Inamori Research Institute of Science, Kyoto, Japan.
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8
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Ren L, Liu L, Song X, Zhao T, Xing X, Feng YP, Chen J, Teo KL. Manipulation of the Topological Ferromagnetic State in a Weyl Semimetal by Spin-Orbit Torque. NANO LETTERS 2023; 23:3394-3400. [PMID: 37043331 DOI: 10.1021/acs.nanolett.3c00410] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Magnetic Weyl semimetals (MWSMs) exhibit unconventional transport phenomena, such as large anomalous Hall (and Nernst) effects, which are absent in spatial inversion asymmetry WSMs. Compared with its nonmagnetic counterpart, the magnetic state of a MWSM provides an alternative way for the modulation of topology. Spin-orbit torque (SOT), as an effective means of electrically controlling the magnetic states of ferromagnets, may be used to manipulate the topological magnetic states of MWSMs. Here we confirm the MWSM state of high-quality Co2MnGa film by systematically investigating the transport measurements and demonstrating that the magnetization and topology of Co2MnGa can be electrically manipulated. The electrical and magnetic optical measurements further reveal that the current-induced SOT switches the topological magnetic state in a 180-degree manner by applying positive/negative current pulses and in a 90-degree manner by alternately applying two orthogonal current pulses. This work opens up more opportunities for spintronic applications based on topological materials.
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Affiliation(s)
- Lizhu Ren
- Department of Electrical and Computer Engineering, National University of Singapore, 117576, Singapore
| | - Liang Liu
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- Department of Materials Science and Engineering, National University of Singapore, 117575, Singapore
| | - Xiaohe Song
- Integrative Sciences and Engineering Programme, NUS Graduate School, National University of Singapore, 119077, Singapore
- Department of Physics, National University of Singapore, 117551, Singapore
| | - Tieyang Zhao
- Department of Materials Science and Engineering, National University of Singapore, 117575, Singapore
| | - Xiangjun Xing
- School of Physics and Optoelectronic Engineering, Guangdong University of Technology, Guangzhou 510006, China
| | - Yuan Ping Feng
- Department of Physics, National University of Singapore, 117551, 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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9
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Qiu H, Seifert TS, Huang L, Zhou Y, Kašpar Z, Zhang C, Wu J, Fan K, Zhang Q, Wu D, Kampfrath T, Song C, Jin B, Chen J, Wu P. Terahertz Spin Current Dynamics in Antiferromagnetic Hematite. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023:e2300512. [PMID: 37083225 DOI: 10.1002/advs.202300512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 03/10/2023] [Indexed: 05/03/2023]
Abstract
An important vision of modern magnetic research is to use antiferromagnets (AFMs) as controllable and active ultrafast components in spintronic devices. Hematite (α-Fe2 O3 ) is a promising model material in this respect because its pronounced Dzyaloshinskii-Moriya interaction leads to the coexistence of antiferromagnetism and weak ferromagnetism. Here, femtosecond laser pulses are used to drive terahertz (THz) spin currents from α-Fe2 O3 into an adjacent Pt layer. Two contributions to the generation of the spin current with distinctly different dynamics are found: the impulsive stimulated Raman scatting that relies on the AFM order and the ultrafast spin Seebeck effect that relies on the net magnetization. The total THz spin current dynamics can be manipulated by a medium-strength magnetic field below 1 T. The control of the THz spin current achieved in α-Fe2 O3 opens the pathway toward tailoring the exact spin current dynamics from ultrafast AFM spin sources.
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Affiliation(s)
- Hongsong Qiu
- Research Institute of Superconductor Electronics (RISE), School of Electronic Science and Engineering, Nanjing University, Nanjing, 210023, P. R. China
| | - Tom S Seifert
- Department of Physics, Freie Universität Berlin, 14195, Berlin, Germany
| | - Lin Huang
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing, 100084, P. R. China
| | - Yongjian Zhou
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing, 100084, P. R. China
| | - Zdeněk Kašpar
- Department of Physics, Freie Universität Berlin, 14195, Berlin, Germany
| | - Caihong Zhang
- Research Institute of Superconductor Electronics (RISE), School of Electronic Science and Engineering, Nanjing University, Nanjing, 210023, P. R. China
| | - Jingbo Wu
- Research Institute of Superconductor Electronics (RISE), School of Electronic Science and Engineering, Nanjing University, Nanjing, 210023, P. R. China
| | - Kebin Fan
- Research Institute of Superconductor Electronics (RISE), School of Electronic Science and Engineering, Nanjing University, Nanjing, 210023, P. R. China
| | - Qi Zhang
- Department of Physics, Nanjing University, Nanjing, 210023, P. R. China
| | - Di Wu
- National Laboratory of Solid State Microstructures, Jiangsu Provincial Key Laboratory for Nanotechnology, Collaborative Innovation Center of Advanced Microstructures and Department of Physics, Nanjing University, Nanjing, 210023, P. R. China
| | - Tobias Kampfrath
- Department of Physics, Freie Universität Berlin, 14195, Berlin, Germany
| | - Cheng Song
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing, 100084, P. R. China
| | - Biaobing Jin
- Research Institute of Superconductor Electronics (RISE), School of Electronic Science and Engineering, Nanjing University, Nanjing, 210023, P. R. China
| | - Jian Chen
- Research Institute of Superconductor Electronics (RISE), School of Electronic Science and Engineering, Nanjing University, Nanjing, 210023, P. R. China
| | - Peiheng Wu
- Research Institute of Superconductor Electronics (RISE), School of Electronic Science and Engineering, Nanjing University, Nanjing, 210023, P. R. China
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10
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Zhu L, Ralph DC. Strong variation of spin-orbit torques with relative spin relaxation rates in ferrimagnets. Nat Commun 2023; 14:1778. [PMID: 36997579 PMCID: PMC10063689 DOI: 10.1038/s41467-023-37506-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 03/20/2023] [Indexed: 04/03/2023] Open
Abstract
Spin-orbit torques (SOTs) have been widely understood as an interfacial transfer of spin that is independent of the bulk properties of the magnetic layer. Here, we report that SOTs acting on ferrimagnetic FexTb1-x layers decrease and vanish upon approaching the magnetic compensation point because the rate of spin transfer to the magnetization becomes much slower than the rate of spin relaxation into the crystal lattice due to spin-orbit scattering. These results indicate that the relative rates of competing spin relaxation processes within magnetic layers play a critical role in determining the strength of SOTs, which provides a unified understanding for the diverse and even seemingly puzzling SOT phenomena in ferromagnetic and compensated systems. Our work indicates that spin-orbit scattering within the magnet should be minimized for efficient SOT devices. We also find that the interfacial spin-mixing conductance of interfaces of ferrimagnetic alloys (such as FexTb1-x) is as large as that of 3d ferromagnets and insensitive to the degree of magnetic compensation.
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Affiliation(s)
- Lijun Zhu
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, China.
- College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Daniel C Ralph
- Cornell University, Ithaca, NY, 14850, USA
- Kavli Institute at Cornell, Ithaca, NY, 14850, USA
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11
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Xu J, He J, Zhou JS, Qu D, Huang SY, Chien CL. Observation of Vector Spin Seebeck Effect in a Noncollinear Antiferromagnet. PHYSICAL REVIEW LETTERS 2022; 129:117202. [PMID: 36154395 DOI: 10.1103/physrevlett.129.117202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2022] [Revised: 05/16/2022] [Accepted: 08/15/2022] [Indexed: 06/16/2023]
Abstract
Spintronic phenomena to date have been established in magnets with collinear moments, where the spin injection through the spin Seebeck effect (SSE) is always along the out-of-plane direction. Here, we report the observation of a vector SSE in a noncollinear antiferromagnet (AF) LuFeO_{3}, where temperature gradient along the out-of-plane and also the in-plane directions can both inject a pure spin current and generate a voltage in the heavy metal via the inverse spin Hall effect (ISHE). We show that the thermovoltages are due to the magnetization from canted spins in LuFeO_{3}. Furthermore, in contrast to the challenges of generating, manipulating, and detecting spin current in collinear AFs, the vector SSE in LuFeO_{3} is readily viable in zero magnetic field and can be controlled by a small magnetic field of about 150 Oe at room temperature. The noncollinear AFs expand new realms for exploring spin phenomena and provide a new route to low-field antiferromagnetic spin caloritronics and magnonics.
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Affiliation(s)
- Jinsong Xu
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Jiaming He
- Department of Mechanical Engineering, University of Texas at Austin, Austin, Texas 78712, USA
| | - J-S Zhou
- Department of Mechanical Engineering, University of Texas at Austin, Austin, Texas 78712, USA
| | - Danru Qu
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
| | - Ssu-Yen Huang
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan
| | - C L Chien
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan
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12
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Zhang P, Chou CT, Yun H, McGoldrick BC, Hou JT, Mkhoyan KA, Liu L. Control of Néel Vector with Spin-Orbit Torques in an Antiferromagnetic Insulator with Tilted Easy Plane. PHYSICAL REVIEW LETTERS 2022; 129:017203. [PMID: 35841567 DOI: 10.1103/physrevlett.129.017203] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Revised: 04/29/2022] [Accepted: 06/02/2022] [Indexed: 05/27/2023]
Abstract
Injecting spin currents into antiferromagnets and realizing efficient spin-orbit-torque switching represents a challenging topic. Because of the diminishing magnetic susceptibility, current-induced antiferromagnetic dynamics remain poorly characterized, complicated by spurious effects. Here, by growing a thin film antiferromagnet, α-Fe_{2}O_{3}, along its nonbasal plane orientation, we realize a configuration where the spin-orbit torque from an injected spin current can unambiguously rotate and switch the Néel vector within the tilted easy plane, with an efficiency comparable to that of classical ferrimagnetic insulators. Our study introduces a new platform for quantitatively characterizing switching and oscillation dynamics in antiferromagnets.
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Affiliation(s)
- Pengxiang Zhang
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Chung-Tao Chou
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Hwanhui Yun
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Brooke C McGoldrick
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Justin T Hou
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - K Andre Mkhoyan
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Luqiao Liu
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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13
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Cheng Y, Cogulu E, Resnick RD, Michel JJ, Statuto NN, Kent AD, Yang F. Third harmonic characterization of antiferromagnetic heterostructures. Nat Commun 2022; 13:3659. [PMID: 35760929 PMCID: PMC9237044 DOI: 10.1038/s41467-022-31451-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 06/17/2022] [Indexed: 11/19/2022] Open
Abstract
Electrical switching of antiferromagnets is an exciting recent development in spintronics, which promises active antiferromagnetic devices with high speed and low energy cost. In this emerging field, there is an active debate about the mechanisms of current-driven switching of antiferromagnets. For heavy-metal/ferromagnet systems, harmonic characterization is a powerful tool to quantify current-induced spin-orbit torques and spin Seebeck effect and elucidate current-induced switching. However, harmonic measurement of spin-orbit torques has never been verified in antiferromagnetic heterostructures. Here, we report harmonic measurements in Pt/α-Fe2O3 bilayers, which are explained by our modeling of higher-order harmonic voltages. As compared with ferromagnetic heterostructures where all current-induced effects appear in the second harmonic signals, the damping-like torque and thermally-induced magnetoelastic effect contributions in Pt/α-Fe2O3 emerge in the third harmonic voltage. Our results provide a new path to probe the current-induced magnetization dynamics in antiferromagnets, promoting the application of antiferromagnetic spintronic devices.
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Affiliation(s)
- Yang Cheng
- Department of Physics, The Ohio State University, Columbus, OH, 43210, USA
- Department of Electrical and Computer Engineering, and Department of Physics and Astronomy, University of California, Los Angeles, CA, 90095, USA
| | - Egecan Cogulu
- Department of Physics, Center for Quantum Phenomena, New York University, New York, NY, 10003, USA
| | - Rachel D Resnick
- Department of Physics, The Ohio State University, Columbus, OH, 43210, USA
| | - Justin J Michel
- Department of Physics, The Ohio State University, Columbus, OH, 43210, USA
| | - Nahuel N Statuto
- Department of Physics, Center for Quantum Phenomena, New York University, New York, NY, 10003, USA
| | - Andrew D Kent
- Department of Physics, Center for Quantum Phenomena, New York University, New York, NY, 10003, USA
| | - Fengyuan Yang
- Department of Physics, The Ohio State University, Columbus, OH, 43210, USA.
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14
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Cogulu E, Zhang H, Statuto NN, Cheng Y, Yang F, Cheng R, Kent AD. Quantifying Spin-Orbit Torques in Antiferromagnet-Heavy-Metal Heterostructures. PHYSICAL REVIEW LETTERS 2022; 128:247204. [PMID: 35776458 DOI: 10.1103/physrevlett.128.247204] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 06/02/2022] [Indexed: 06/15/2023]
Abstract
The effect of spin currents on the magnetic order of insulating antiferromagnets (AFMs) is of fundamental interest and can enable new applications. Toward this goal, characterizing the spin-orbit torques (SOTs) associated with AFM-heavy-metal (HM) interfaces is important. Here we report the full angular dependence of the harmonic Hall voltages in a predominantly easy-plane AFM, epitaxial c-axis oriented α-Fe_{2}O_{3} films, with an interface to Pt. By modeling the harmonic Hall signals together with the α-Fe_{2}O_{3} magnetic parameters, we determine the amplitudes of fieldlike and dampinglike SOTs. Out-of-plane field scans are shown to be essential to determining the dampinglike component of the torques. In contrast to ferromagnetic-heavy-metal heterostructures, our results demonstrate that the fieldlike torques are significantly larger than the dampinglike torques, which we correlate with the presence of a large imaginary component of the interface spin-mixing conductance. Our work demonstrates a direct way of characterizing SOTs in AFM-HM heterostructures.
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Affiliation(s)
- Egecan Cogulu
- Center for Quantum Phenomena, Department of Physics, New York University, New York 10003, USA
| | - Hantao Zhang
- Department of Electrical and Computer Engineering, University of California, Riverside, California 92521, USA
| | - Nahuel N Statuto
- Center for Quantum Phenomena, Department of Physics, New York University, New York 10003, USA
| | - Yang Cheng
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA
| | - Fengyuan Yang
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA
| | - Ran Cheng
- Department of Electrical and Computer Engineering, University of California, Riverside, California 92521, USA
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - Andrew D Kent
- Center for Quantum Phenomena, Department of Physics, New York University, New York 10003, USA
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15
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Zhu D, Zhang T, Fu X, Hao R, Hamzić A, Yang H, Zhang X, Zhang H, Du A, Xiong D, Shi K, Yan S, Zhang S, Fert A, Zhao W. Sign Change of Spin-Orbit Torque in Pt/NiO/CoFeB Structures. PHYSICAL REVIEW LETTERS 2022; 128:217702. [PMID: 35687442 DOI: 10.1103/physrevlett.128.217702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 01/30/2022] [Accepted: 04/20/2022] [Indexed: 06/15/2023]
Abstract
Antiferromagnetic insulators have recently been proved to support spin current efficiently. Here, we report the dampinglike spin-orbit torque (SOT) in Pt/NiO/CoFeB has a strong temperature dependence and reverses the sign below certain temperatures, which is different from the slight variation with temperature in the Pt/CoFeB bilayer. The negative dampinglike SOT at low temperatures is proposed to be mediated by the magnetic interactions that tie with the "exchange bias" in Pt/NiO/CoFeB, in contrast to the thermal-magnon-mediated scenario at high temperatures. Our results highlight the promise to control the SOT through tuning the magnetic structure in multilayers.
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Affiliation(s)
- Dapeng Zhu
- Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, China
- Beihang-Goertek Joint Microelectronics Institute, Qingdao Research Institute, Beihang University, Qingdao 266000, China
| | - Tianrui Zhang
- Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, China
| | - Xiao Fu
- Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, China
- Beihang-Goertek Joint Microelectronics Institute, Qingdao Research Institute, Beihang University, Qingdao 266000, China
| | - Runrun Hao
- Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, China
- Beihang-Goertek Joint Microelectronics Institute, Qingdao Research Institute, Beihang University, Qingdao 266000, China
| | - Amir Hamzić
- Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, China
- Department of Physics, Faculty of Science, University of Zagreb, Zagreb HR-10001, Croatia
| | - Huaiwen Yang
- Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, China
- Beihang-Goertek Joint Microelectronics Institute, Qingdao Research Institute, Beihang University, Qingdao 266000, China
| | - Xueying Zhang
- Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, China
- Beihang-Goertek Joint Microelectronics Institute, Qingdao Research Institute, Beihang University, Qingdao 266000, China
| | - Hui Zhang
- Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, China
| | - Ao Du
- Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, China
| | - Danrong Xiong
- Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, China
| | - Kewen Shi
- Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, China
| | - Shishen Yan
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China
| | - Shufeng Zhang
- Department of Physics, University of Arizona, Tucson, Arizona 85721, USA
| | - Albert Fert
- Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, China
- Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, Palaiseau 91767, France
| | - Weisheng Zhao
- Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, China
- Beihang-Goertek Joint Microelectronics Institute, Qingdao Research Institute, Beihang University, Qingdao 266000, China
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16
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Xu J, Xia J, Zhang X, Zhou C, Shi D, Chen H, Wu T, Li Q, Ding H, Zhou Y, Wu Y. Exchange-Torque-Triggered Fast Switching of Antiferromagnetic Domains. PHYSICAL REVIEW LETTERS 2022; 128:137201. [PMID: 35426702 DOI: 10.1103/physrevlett.128.137201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 01/27/2022] [Accepted: 03/04/2022] [Indexed: 06/14/2023]
Abstract
The antiferromagnet is considered to be a promising hosting material for the next generation of magnetic storage due to its high stability and stray-field-free property. Understanding the switching properties of the antiferromagnetic (AFM) domain state is critical for developing AFM spintronics. By utilizing the magneto-optical birefringence effect, we experimentally demonstrate the switching rate of the AFM domain can be enhanced by more than 2 orders of magnitude through applying an alternating square-wave field on a single crystalline Fe/CoO bilayer. The observed extraordinary speed can be much faster than that triggered by a constant field with the same amplitude. The effect can be understood as the efficient suppression of the pinning of AFM domain walls by the strong exchange torque triggered by the reversal of the Fe magnetization, as revealed by spin dynamics simulations. Our finding opens up new opportunities to design the antiferromagnet-based spintronic devices utilizing the ferromagnet-antiferromagnet heterostructure.
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Affiliation(s)
- Jia Xu
- Department of Physics and State Key Laboratory of Surface Physics, Fudan University, Shanghai 200433, China
- Institute of Physics, Shaanxi University of Technology, Hanzhong 723001, China
| | - Jing Xia
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China
- College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610068, China
| | - Xichao Zhang
- Department of Electrical and Computer Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553, Japan
| | - Chao Zhou
- Department of Physics and State Key Laboratory of Surface Physics, Fudan University, Shanghai 200433, China
- Institute of Physics, Shaanxi University of Technology, Hanzhong 723001, China
| | - Dong Shi
- Department of Physics and State Key Laboratory of Surface Physics, Fudan University, Shanghai 200433, China
| | - Haoran Chen
- Department of Physics and State Key Laboratory of Surface Physics, Fudan University, Shanghai 200433, China
| | - Tong Wu
- Department of Physics and State Key Laboratory of Surface Physics, Fudan University, Shanghai 200433, China
| | - Qian Li
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China
| | - Haifeng Ding
- National Laboratory of Solid State Microstructures, Department of Physics, Nanjing University, Nanjing 210093, China
| | - Yan Zhou
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China
| | - Yizheng Wu
- Department of Physics and State Key Laboratory of Surface Physics, Fudan University, Shanghai 200433, China
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
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17
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Current-induced Néel order switching facilitated by magnetic phase transition. Nat Commun 2022; 13:1629. [PMID: 35347132 PMCID: PMC8960908 DOI: 10.1038/s41467-022-29170-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2021] [Accepted: 02/11/2022] [Indexed: 11/24/2022] Open
Abstract
Terahertz (THz) spin dynamics and vanishing stray field make antiferromagnetic (AFM) materials the most promising candidate for the next-generation magnetic memory technology with revolutionary storage density and writing speed. However, owing to the extremely large exchange energy barriers, energy-efficient manipulation has been a fundamental challenge in AFM systems. Here, we report an electrical writing of antiferromagnetic orders through a record-low current density on the order of 106 A cm−2 facilitated by the unique AFM-ferromagnetic (FM) phase transition in FeRh. By introducing a transient FM state via current-induced Joule heating, the spin-orbit torque can switch the AFM order parameter by 90° with a reduced writing current density similar to ordinary FM materials. This mechanism is further verified by measuring the temperature and magnetic bias field dependences, where the X-ray magnetic linear dichroism (XMLD) results confirm the AFM switching besides the electrical transport measurement. Our findings demonstrate the exciting possibility of writing operations in AFM-based devices with a lower current density, opening a new pathway towards pure AFM memory applications. Electrical manipulation of antiferromagnetic order is crucial for future memory devices, but existing switching schemes require a large current density. Here, the authors achieve record low current density switching in FeRh by taking advantage of its antiferromagnetic to ferromagnetic phase transition.
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18
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Bossini D, Pancaldi M, Soumah L, Basini M, Mertens F, Cinchetti M, Satoh T, Gomonay O, Bonetti S. Ultrafast Amplification and Nonlinear Magnetoelastic Coupling of Coherent Magnon Modes in an Antiferromagnet. PHYSICAL REVIEW LETTERS 2021; 127:077202. [PMID: 34459640 DOI: 10.1103/physrevlett.127.077202] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 05/22/2021] [Accepted: 06/24/2021] [Indexed: 06/13/2023]
Abstract
We investigate the role of domain walls in the ultrafast magnon dynamics of an antiferromagnetic NiO single crystal in a pump-probe experiment with variable pump photon energy. Analyzing the amplitude of the energy-dependent photoinduced ultrafast spin dynamics, we detect a yet unreported coupling between the material's characteristic terahertz- and gigahertz-magnon modes. We explain this unexpected coupling between two orthogonal eigenstates of the corresponding Hamiltonian by modeling the magnetoelastic interaction between spins in different domains. We find that such interaction, in the nonlinear regime, couples the two different magnon modes via the domain walls and it can be optically exploited via the exciton-magnon resonance.
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Affiliation(s)
- D Bossini
- Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457 Konstanz, Germany
| | - M Pancaldi
- Department of Physics, Stockholm University, 106 91 Stockholm, Sweden
| | - L Soumah
- Department of Physics, Stockholm University, 106 91 Stockholm, Sweden
| | - M Basini
- Department of Physics, Stockholm University, 106 91 Stockholm, Sweden
| | - F Mertens
- Experimentelle Physik VI, Technische Universität Dortmund, Otto-Hahn Straße 4, 44227 Dortmund, Germany
| | - M Cinchetti
- Experimentelle Physik VI, Technische Universität Dortmund, Otto-Hahn Straße 4, 44227 Dortmund, Germany
| | - T Satoh
- Department of Physics, Tokyo Institute of Technology, Tokyo 152-8551, Japan
| | - O Gomonay
- Institut für Physik, Johannes Gutenberg Universität Mainz, D-55099 Mainz, Germany
| | - S Bonetti
- Department of Physics, Stockholm University, 106 91 Stockholm, Sweden
- Department of Molecular Sciences and Nanosystems, Ca' Foscari University of Venice, 30172 Venezia-Mestre, Italy
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19
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Abstract
Antiferromagnetic oxides have recently gained much attention because of the possibility to manipulate electrically and optically the Néel vectors in these materials. Their ultrafast spin dynamics, long spin diffusion length and immunity to large magnetic fields make them attractive candidates for spintronic applications. Additionally, there have been many studies on spin wave and magnon transport in single crystals of these oxides. However, the successful applications of the antiferromagnetic oxides will require similar spin transport properties in thin films. In this work, we systematically show the sputtering deposition method for two uniaxial antiferromagnetic oxides, namely Cr2O3 and α-Fe2O3, on A-plane sapphire substrates, and identify the optimized deposition conditions for epitaxial films with low surface roughness. We also confirm the antiferromagnetic properties of the thin films. The deposition method developed in this article will be important for studying the magnon transport in these epitaxial antiferromagnetic thin films.
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20
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Observation of current-induced switching in non-collinear antiferromagnetic IrMn 3 by differential voltage measurements. Nat Commun 2021; 12:3828. [PMID: 34158511 PMCID: PMC8219769 DOI: 10.1038/s41467-021-24237-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 06/09/2021] [Indexed: 11/19/2022] Open
Abstract
There is accelerating interest in developing memory devices using antiferromagnetic (AFM) materials, motivated by the possibility for electrically controlling AFM order via spin-orbit torques, and its read-out via magnetoresistive effects. Recent studies have shown, however, that high current densities create non-magnetic contributions to resistive switching signals in AFM/heavy metal (AFM/HM) bilayers, complicating their interpretation. Here we introduce an experimental protocol to unambiguously distinguish current-induced magnetic and nonmagnetic switching signals in AFM/HM structures, and demonstrate it in IrMn3/Pt devices. A six-terminal double-cross device is constructed, with an IrMn3 pillar placed on one cross. The differential voltage is measured between the two crosses with and without IrMn3 after each switching attempt. For a wide range of current densities, reversible switching is observed only when write currents pass through the cross with the IrMn3 pillar, eliminating any possibility of non-magnetic switching artifacts. Micromagnetic simulations support our findings, indicating a complex domain-mediated switching process. Anti-ferromagnetic based memories have a wide range of advantages over their ferromagnetic counterparts, however, their electrical signatures of switching are complicated by spurious signals. Here, Arpaci et al demonstrate an experimental method to distinguish between anti-ferromagnetic switching, and such spurious signatures.
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21
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Reversible hydrogen control of antiferromagnetic anisotropy in α-Fe 2O 3. Nat Commun 2021; 12:1668. [PMID: 33712582 PMCID: PMC7954816 DOI: 10.1038/s41467-021-21807-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 02/04/2021] [Indexed: 11/14/2022] Open
Abstract
Antiferromagnetic insulators are a ubiquitous class of magnetic materials, holding the promise of low-dissipation spin-based computing devices that can display ultra-fast switching and are robust against stray fields. However, their imperviousness to magnetic fields also makes them difficult to control in a reversible and scalable manner. Here we demonstrate a novel proof-of-principle ionic approach to control the spin reorientation (Morin) transition reversibly in the common antiferromagnetic insulator α-Fe2O3 (haematite) – now an emerging spintronic material that hosts topological antiferromagnetic spin-textures and long magnon-diffusion lengths. We use a low-temperature catalytic-spillover process involving the post-growth incorporation or removal of hydrogen from α-Fe2O3 thin films. Hydrogenation drives pronounced changes in its magnetic anisotropy, Néel vector orientation and canted magnetism via electron injection and local distortions. We explain these effects with a detailed magnetic anisotropy model and first-principles calculations. Tailoring our work for future applications, we demonstrate reversible control of the room-temperature spin-state by doping/expelling hydrogen in Rh-substituted α-Fe2O3. One major challenge for antiferromagnetic spintronics is how to control the antiferromagnetic state. Here Jani et al. demonstrate the reversible ionic control of the room-temperature magnetic anisotropy and spin reorientation transition in haematite, via the incorporation and removal of hydrogen.
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22
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Antiferromagnetic half-skyrmions and bimerons at room temperature. Nature 2021; 590:74-79. [PMID: 33536652 DOI: 10.1038/s41586-021-03219-6] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 11/16/2020] [Indexed: 01/30/2023]
Abstract
In the quest for post-CMOS (complementary metal-oxide-semiconductor) technologies, driven by the need for improved efficiency and performance, topologically protected ferromagnetic 'whirls' such as skyrmions1-8 and their anti-particles have shown great promise as solitonic information carriers in racetrack memory-in-logic or neuromorphic devices1,9-11. However, the presence of dipolar fields in ferromagnets, which restricts the formation of ultrasmall topological textures3,6,8,9,12, and the deleterious skyrmion Hall effect, when skyrmions are driven by spin torques9,10,12, have thus far inhibited their practical implementation. Antiferromagnetic analogues, which are predicted to demonstrate relativistic dynamics, fast deflection-free motion and size scaling, have recently become the subject of intense focus9,13-19, but they have yet to be experimentally demonstrated in natural antiferromagnetic systems. Here we realize a family of topological antiferromagnetic spin textures in α-Fe2O3-an Earth-abundant oxide insulator-capped with a platinum overlayer. By exploiting a first-order analogue of the Kibble-Zurek mechanism20,21, we stabilize exotic merons and antimerons (half-skyrmions)8 and their pairs (bimerons)16,22, which can be erased by magnetic fields and regenerated by temperature cycling. These structures have characteristic sizes of the order of 100 nanometres and can be chemically controlled via precise tuning of the exchange and anisotropy, with pathways through which further scaling may be achieved. Driven by current-based spin torques from the heavy-metal overlayer, some of these antiferromagnetic textures could emerge as prime candidates for low-energy antiferromagnetic spintronics at room temperature1,9-11,23.
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23
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Mitrofanov A, Urazhdin S. Nonclassical Spin Transfer Effects in an Antiferromagnet. PHYSICAL REVIEW LETTERS 2021; 126:037203. [PMID: 33543951 DOI: 10.1103/physrevlett.126.037203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 12/23/2020] [Indexed: 06/12/2023]
Abstract
We simulate scattering of electrons by a chain of antiferromagnetically coupled quantum Heisenberg spins, to analyze spin-transfer effects not described by the classical models of magnetism. Our simulations demonstrate efficient excitation of dynamical states that would be forbidden by the semiclassical symmetries, such as generation of multiple magnetic excitation quanta by a single electron. Furthermore, quantum interference of spin wave functions enables generation of magnetization dynamics with amplitudes exceeding the transferred magnetic moment. The efficiency of excitation is almost independent of the electron spin polarization, and is governed mainly by the transfer of energy. Nonclassical spin transfer may thus enable efficient electronic control of antiferromagnets not limited by the classical constraints.
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Affiliation(s)
| | - Sergei Urazhdin
- Department of Physics, Emory University, Atlanta, Georgia 30322, USA
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Meer H, Schreiber F, Schmitt C, Ramos R, Saitoh E, Gomonay O, Sinova J, Baldrati L, Kläui M. Direct Imaging of Current-Induced Antiferromagnetic Switching Revealing a Pure Thermomagnetoelastic Switching Mechanism in NiO. NANO LETTERS 2021; 21:114-119. [PMID: 33306407 DOI: 10.1021/acs.nanolett.0c03367] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We unravel the origin of current-induced magnetic switching of insulating antiferromagnet/heavy metal systems. We utilize concurrent transport and magneto-optical measurements to image the switching of antiferromagnetic domains in specially engineered devices of NiO/Pt bilayers. Different electrical pulsing and device geometries reveal different final states of the switching with respect to the current direction. We can explain these through simulations of the temperature-induced strain, and we identify the thermomagnetoelastic switching mechanism combined with thermal excitations as the origin, in which the final state is defined by the strain distributions and heat is required to switch the antiferromagnetic domains. We show that such a potentially very versatile noncontact mechanism can explain the previously reported contradicting observations of the switching final state, which were attributed to spin-orbit torque mechanisms.
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Affiliation(s)
- Hendrik Meer
- Institute of Physics, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany
| | - Felix Schreiber
- Institute of Physics, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany
| | - Christin Schmitt
- Institute of Physics, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany
| | - Rafael Ramos
- WPI-Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
- Centro de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS), Departamento de Química-Física, Universidade de Santiago de Compostela, Santiago de Compostela 15782, Spain
| | - Eiji Saitoh
- WPI-Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan
- Center for Spintronics Research Network, Tohoku University, Sendai 980-8577, Japan
- Department of Applied Physics, The University of Tokyo, Tokyo 113-8656, Japan
| | - Olena Gomonay
- Institute of Physics, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany
| | - Jairo Sinova
- Institute of Physics, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany
- Institut of Physics, Academy of Sciences of the Czech Republic, Praha 11720, Czech Republic
- Graduate School of Excellence Materials Science in Mainz, 55128 Mainz, Germany
| | - Lorenzo Baldrati
- Institute of Physics, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany
| | - Mathias Kläui
- Institute of Physics, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany
- Graduate School of Excellence Materials Science in Mainz, 55128 Mainz, Germany
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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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Baldrati L, Schmitt C, Gomonay O, Lebrun R, Ramos R, Saitoh E, Sinova J, Kläui M. Efficient Spin Torques in Antiferromagnetic CoO/Pt Quantified by Comparing Field- and Current-Induced Switching. PHYSICAL REVIEW LETTERS 2020; 125:077201. [PMID: 32857543 DOI: 10.1103/physrevlett.125.077201] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 07/02/2020] [Accepted: 07/10/2020] [Indexed: 06/11/2023]
Abstract
We achieve current-induced switching in collinear insulating antiferromagnetic CoO/Pt, with fourfold in-plane magnetic anisotropy. This is measured electrically by spin Hall magnetoresistance and confirmed by the magnetic field-induced spin-flop transition of the CoO layer. By applying current pulses and magnetic fields, we quantify the efficiency of the acting current-induced torques and estimate a current-field equivalence ratio of 4×10^{-11} T A^{-1} m^{2}. The Néel vector final state (n⊥j) is in line with a thermomagnetoelastic switching mechanism for a negative magnetoelastic constant of the CoO.
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Affiliation(s)
- L Baldrati
- Institute of Physics, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany
| | - C Schmitt
- Institute of Physics, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany
| | - O Gomonay
- Institute of Physics, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany
| | - R Lebrun
- Institute of Physics, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany
- Unité Mixte de Physique CNRS, Thales, Université Paris-Sud, Université Paris-Saclay, Palaiseau 91767, France
| | - R Ramos
- WPI-Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - E Saitoh
- WPI-Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan
- Center for Spintronics Research Network, Tohoku University, Sendai 980-8577, Japan
- Department of Applied Physics, The University of Tokyo, Tokyo 113-8656, Japan
| | - J Sinova
- Institute of Physics, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany
- Institute of Physics, Academy of Sciences of the Czech Republic, Praha 11720, Czech Republic
- Graduate School of Excellence Materials Science in Mainz, 55128 Mainz, Germany
| | - M Kläui
- Institute of Physics, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany
- Graduate School of Excellence Materials Science in Mainz, 55128 Mainz, Germany
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Yan H, Feng Z, Qin P, Zhou X, Guo H, Wang X, Chen H, Zhang X, Wu H, Jiang C, Liu Z. Electric-Field-Controlled Antiferromagnetic Spintronic Devices. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1905603. [PMID: 32048366 DOI: 10.1002/adma.201905603] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 11/21/2019] [Indexed: 06/10/2023]
Abstract
In recent years, the field of antiferromagnetic spintronics has been substantially advanced. Electric-field control is a promising approach for achieving ultralow power spintronic devices via suppressing Joule heating. Here, cutting-edge research, including electric-field modulation of antiferromagnetic spintronic devices using strain, ionic liquids, dielectric materials, and electrochemical ionic migration, is comprehensively reviewed. Various emergent topics such as the Néel spin-orbit torque, chiral spintronics, topological antiferromagnetic spintronics, anisotropic magnetoresistance, memory devices, 2D magnetism, and magneto-ionic modulation with respect to antiferromagnets are examined. In conclusion, the possibility of realizing high-quality room-temperature antiferromagnetic tunnel junctions, antiferromagnetic spin logic devices, and artificial antiferromagnetic neurons is highlighted. It is expected that this work provides an appropriate and forward-looking perspective that will promote the rapid development of this field.
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Affiliation(s)
- Han Yan
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Zexin Feng
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Peixin Qin
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Xiaorong Zhou
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Huixin Guo
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Xiaoning Wang
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Hongyu Chen
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Xin Zhang
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Haojiang Wu
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Chengbao Jiang
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Zhiqi Liu
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
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