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Subedi MM, Deng K, Flebus B, Sklenar J. Even-odd-layer-dependent symmetry breaking in synthetic antiferromagnets. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:375802. [PMID: 38843803 DOI: 10.1088/1361-648x/ad5508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Accepted: 06/06/2024] [Indexed: 06/21/2024]
Abstract
In this work we examine synthetic antiferromagnetic structures consisting of two, three, and four antiferromagnetic coupled layers, i.e. bilayers, trilayers, and tetralayers. We vary the thickness of the ferromagnetic layers across all structures and, using a macrospin formalism, find that the nearest neighbor exchange interaction between layers is consistent across all structures for a given thickness of the ferromagnetic layer. Our model and experimental results demonstrate significant differences in how the static equilibrium states of even and odd-layered structures evolve as a function of the external field. Even layered structures continuously evolve from a collinear antiferromagnetic state to a spin canted non-collinear magnetic configuration that is mirror-symmetric about the external field. In contrast, odd-layered structures begin with a ferrimagnetic ground state; at a critical field, the ferrimagnetic ground state evolves into a non-collinear state with broken symmetry. Specifically, the magnetic moments found in the odd-layered samples possess stable static equilibrium states that are no longer mirror-symmetric about the external field after a critical field is reached.
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Affiliation(s)
- M M Subedi
- Department of Physics and Astronomy, Wayne State University, Detroit, MI 48202, United States of America
| | - K Deng
- Department of Physics, Boston College, 140 Commonwealth Avenue, Chestnut Hill, MA 02467, United States of America
| | - B Flebus
- Department of Physics, Boston College, 140 Commonwealth Avenue, Chestnut Hill, MA 02467, United States of America
| | - J Sklenar
- Department of Physics and Astronomy, Wayne State University, Detroit, MI 48202, United States of America
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Zhou Y, Li S, Liang X, Zhou Y. Topological Spin Textures: Basic Physics and Devices. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2312935. [PMID: 38861696 DOI: 10.1002/adma.202312935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 05/24/2024] [Indexed: 06/13/2024]
Abstract
In the face of escalating modern data storage demands and the constraints of Moore's Law, exploring spintronic solutions, particularly the devices based on magnetic skyrmions, has emerged as a promising frontier in scientific research. Since the first experimental observation of skyrmions, topological spin textures have been extensively studied for their great potential as efficient information carriers in spintronic devices. However, significant challenges have emerged alongside this progress. This review aims to synthesize recent advances in skyrmion research while addressing the major issues encountered in the field. Additionally, current research on promising topological spin structures in addition to skyrmions is summarized. Beyond 2D structures, exploration also extends to 1D magnetic solitons and 3D spin textures. In addition, a diverse array of emerging magnetic materials is introduced, including antiferromagnets and 2D van der Waals magnets, broadening the scope of potential materials hosting topological spin textures. Through a systematic examination of magnetic principles, topological categorization, and the dynamics of spin textures, a comprehensive overview of experimental and theoretical advances in the research of topological magnetism is provided. Finally, both conventional and unconventional applications are summarized based on spin textures proposed thus far. This review provides an outlook on future development in applied spintronics.
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Affiliation(s)
- Yuqing Zhou
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong, 518172, China
| | - Shuang Li
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong, 518172, China
| | - Xue Liang
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong, 518172, China
| | - Yan Zhou
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong, 518172, China
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Yang S, Son JW, Ju TS, Tran DM, Han HS, Park S, Park BH, Moon KW, Hwang C. Magnetic Skyrmion Transistor Gated with Voltage-Controlled Magnetic Anisotropy. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2208881. [PMID: 36511234 DOI: 10.1002/adma.202208881] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 11/27/2022] [Indexed: 06/17/2023]
Abstract
The paradigm shift of information carriers from charge to spin has long been awaited in modern electronics. The invention of the spin-information transistor is expected to be an essential building block for the future development of spintronics. Here, a proof-of-concept experiment of a magnetic skyrmion transistor working at room temperature, which has never been demonstrated experimentally, is introduced. With the spatially uniform control of magnetic anisotropy, the shape and topology of a skyrmion when passing the controlled area can be maintained. The findings will open a new route toward the design and realization of skyrmion-based spintronic devices in the near future.
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Affiliation(s)
- Seungmo Yang
- Quantum Spin Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
| | - Jong Wan Son
- Quantum Spin Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
| | - Tae-Seong Ju
- Quantum Spin Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
- Department of Physics, Pusan National University, Busan, 46241, Republic of Korea
| | - Duc Minh Tran
- Division of Quantum Phases and Devices, Department of Physics, Konkuk University, Seoul, 05029, Republic of Korea
| | - Hee-Sung Han
- Department of Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - Sungkyun Park
- Department of Physics, Pusan National University, Busan, 46241, Republic of Korea
| | - Bae Ho Park
- Division of Quantum Phases and Devices, Department of Physics, Konkuk University, Seoul, 05029, Republic of Korea
| | - Kyoung-Woong Moon
- Quantum Spin Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
| | - Chanyong Hwang
- Quantum Spin Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
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Chen C, Lin T, Niu J, Sun Y, Yang L, Kang W, Lei N. Surface acoustic wave controlled skyrmion-based synapse devices. NANOTECHNOLOGY 2021; 33:115205. [PMID: 34852336 DOI: 10.1088/1361-6528/ac3f14] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 12/01/2021] [Indexed: 06/13/2023]
Abstract
Magnetic skyrmions, which are particle-like spin structures, are promising information carriers for neuromorphic computing devices due to their topological stability and nanoscale size. In this work, we propose controlling magnetic skyrmions by electric-field-excited surface acoustic waves in neuromorphic computing device structures. Our micromagnetic simulations show that the number of created skyrmions, which emulates the synaptic weight parameter, increases monotonically with increases in the amplitude of the surface acoustic waves. Additionally, the efficiency of skyrmion creation is investigated systemically with a wide range of magnetic parameters, and the optimal values are presented accordingly. Finally, the functionalities of short-term plasticity and long-term potentiation are demonstrated via skyrmion excitation by a sequence of surface acoustic waves with different intervals. The application of surface acoustic waves in skyrmionic neuromorphic computing devices paves a novel approach to low-power computing systems.
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Affiliation(s)
- Chao Chen
- Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, People's Republic of China
| | - Tao Lin
- Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, People's Republic of China
| | - Jianteng Niu
- Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, People's Republic of China
| | - Yiming Sun
- Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, People's Republic of China
| | - Liu Yang
- Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, People's Republic of China
| | - Wang Kang
- Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, People's Republic of China
| | - Na Lei
- Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, People's Republic of China
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Bindal N, Nisar A, Dhull S, Kaushik BK. Magnetic Skyrmions: Recent advances and applications. IEEE NANOTECHNOLOGY MAGAZINE 2021. [DOI: 10.1109/mnano.2021.3113215] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Yang S, Moon KW, Ju TS, Kim C, Kim HJ, Kim J, Tran BX, Hong JI, Hwang C. Electrical Generation and Deletion of Magnetic Skyrmion-Bubbles via Vertical Current Injection. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2104406. [PMID: 34569658 DOI: 10.1002/adma.202104406] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 08/28/2021] [Indexed: 06/13/2023]
Abstract
The magnetic skyrmion is a topologically protected spin texture that has attracted much attention as a promising information carrier because of its distinct features of suitability for high-density storage, low power consumption, and stability. One of the skyrmion devices proposed so far is the skyrmion racetrack memory, which is the skyrmion version of the domain-wall racetrack memory. For application in devices, skyrmion racetrack memory requires electrical generation, deletion, and displacement of isolated skyrmions. Despite the progress in experimental demonstrations of skyrmion generation, deletion, and displacement, these three operations have yet to be realized in one device. Here, a route for generating and deleting isolated skyrmion-bubbles through vertical current injection with an explanation of its microscopic origin is presented. By combining the proposed skyrmion-bubble generation/deletion method with the spin-orbit-torque-driven skyrmion shift, a proof-of-concept experimental demonstration of the skyrmion racetrack memory operation in a three-terminal device structure is provided.
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Affiliation(s)
- Seungmo Yang
- Quantum Spin Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
| | - Kyoung-Woong Moon
- Quantum Spin Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
| | - Tae-Seong Ju
- Quantum Spin Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
| | - Changsoo Kim
- Quantum Spin Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
| | - Hyun-Joong Kim
- Quantum Spin Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
| | - Juran Kim
- Quantum Spin Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
| | - Bao Xuan Tran
- Department of Emerging Materials Science, DGIST, Daegu, 42988, Republic of Korea
| | - Jung-Il Hong
- Department of Emerging Materials Science, DGIST, Daegu, 42988, Republic of Korea
| | - Chanyong Hwang
- Quantum Spin Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
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Hassan M, Laureti S, Rinaldi C, Fagiani F, Varotto S, Barucca G, Schmidt NY, Varvaro G, Albrecht M. Perpendicularly magnetized Co/Pd-based magneto-resistive heterostructures on flexible substrates. NANOSCALE ADVANCES 2021; 3:3076-3084. [PMID: 36133649 PMCID: PMC9418425 DOI: 10.1039/d1na00110h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 04/08/2021] [Indexed: 06/14/2023]
Abstract
Flexible magneto-resistive heterostructures have received a great deal of attention over the past few years as they allow for new product paradigms that are not possible with conventional rigid substrates. While the progress and development of systems with longitudinal magnetic anisotropy on non-planar substrates has been remarkable, flexible magneto-resistive heterostructures with perpendicular magnetic anisotropy (PMA) have never been studied despite the possibility to obtain additional functionality and improved performance. To fill this gap, flexible PMA Co/Pd-based giant magneto-resistive (GMR) spin-valve stacks were prepared by using an innovative transfer-and-bonding strategy exploiting the low adhesion of a gold underlayer to SiO x /Si(100) substrates. The approach allows overcoming the limits of the direct deposition on commonly used polymer substrates, whose high surface roughness and low melting temperature could hinder the growth of complex heterostructures with perpendicular magnetic anisotropy. The obtained PMA flexible spin-valves show a sizeable GMR ratio (∼1.5%), which is not affected by the transfer process, and a high robustness against bending as indicated by the slight change of the magneto-resistive properties upon bending, thus allowing for their integration on curved surfaces and the development of a novel class of advanced devices based on flexible magneto-resistive structures with perpendicular magnetic anisotropy. Besides endowing the family of flexible electronics with PMA magneto-resistive heterostructures, the exploitation of the results might apply to high temperature growth processes and to the fabrication of other functional and flexible multilayer materials engineered at the nanoscale.
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Affiliation(s)
- M Hassan
- Consiglio Nazionale delle Ricerche, Istituto di Struttura della Materia, nM2-Lab Via Salaria km 29.300 Monterotondo Scalo (Roma) 00015 Italy
- Università Politecnica delle Marche, Dipartimento SIMAU Via Brecce Bianche Ancona 60131 Italy
| | - S Laureti
- Consiglio Nazionale delle Ricerche, Istituto di Struttura della Materia, nM2-Lab Via Salaria km 29.300 Monterotondo Scalo (Roma) 00015 Italy
| | - C Rinaldi
- Politecnico di Milano, Department of Physics and IFN-CNR via G. Colombo 81 20133 Milano Italy
| | - F Fagiani
- Politecnico di Milano, Department of Physics and IFN-CNR via G. Colombo 81 20133 Milano Italy
| | - S Varotto
- Politecnico di Milano, Department of Physics and IFN-CNR via G. Colombo 81 20133 Milano Italy
| | - G Barucca
- Università Politecnica delle Marche, Dipartimento SIMAU Via Brecce Bianche Ancona 60131 Italy
| | - N Y Schmidt
- University of Augsburg, Institute of Physics Universitätsstraße 1 Nord D-86159 Augsburg Germany
| | - G Varvaro
- Consiglio Nazionale delle Ricerche, Istituto di Struttura della Materia, nM2-Lab Via Salaria km 29.300 Monterotondo Scalo (Roma) 00015 Italy
| | - M Albrecht
- University of Augsburg, Institute of Physics Universitätsstraße 1 Nord D-86159 Augsburg Germany
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