1
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Ji Y, Yang S, Ahn HB, Moon KW, Ju TS, Im MY, Han HS, Lee J, Park SY, Lee C, Kim KJ, Hwang C. Direct Observation of Room-Temperature Magnetic Skyrmion Motion Driven by Ultra-Low Current Density in Van Der Waals Ferromagnets. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2312013. [PMID: 38270245 DOI: 10.1002/adma.202312013] [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: 01/05/2024] [Indexed: 01/26/2024]
Abstract
The recent discovery of room-temperature ferromagnetism in 2D van der Waals (vdW) materials, such as Fe3GaTe2 (FGaT), has garnered significant interest in offering a robust platform for 2D spintronic applications. Various fundamental operations essential for the realization of 2D spintronics devices are experimentally confirmed using these materials at room temperature, such as current-induced magnetization switching or tunneling magnetoresistance. Nevertheless, the potential applications of magnetic skyrmions in FGaT systems at room temperature remain unexplored. In this work, the current-induced generation of magnetic skyrmions in FGaT flakes employing high-resolution magnetic transmission soft X-ray microscopy is introduced, supported by a feasible mechanism based on thermal effects. Furthermore, direct observation of the current-induced magnetic skyrmion motion at room temperature in FGaT flakes is presented with ultra-low threshold current density. This work highlights the potential of FGaT as a foundation for room-temperature-operating 2D skyrmion device applications.
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Affiliation(s)
- Yubin Ji
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea
| | - Seungmo Yang
- Quantum Spin Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
| | - Hyo-Bin Ahn
- SKKU Advanced Institute of Nanotechnology, Sungkyunkwan University, Suwon, 16419, 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
| | - Mi-Young Im
- Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Hee-Sung Han
- Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Materials Science and Engineering, Korea National University of Transportation, Chungju, 27469, Republic of Korea
| | - Jisung Lee
- Center for scientific instrumentation, Korea Basic Science Institute, Daejeon, 34133, Republic of Korea
| | - Seung-Young Park
- Center for scientific instrumentation, Korea Basic Science Institute, Daejeon, 34133, Republic of Korea
| | - Changgu Lee
- School of Mechanical Engineering, Sungykunkwan University, Suwon, 16419, Republic of Korea
| | - Kab-Jin Kim
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea
| | - Chanyong Hwang
- Quantum Spin Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
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2
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Zhang Y, Tang J, Wu Y, Shi M, Xu X, Wang S, Tian M, Du H. Stable skyrmion bundles at room temperature and zero magnetic field in a chiral magnet. Nat Commun 2024; 15:3391. [PMID: 38649678 PMCID: PMC11035646 DOI: 10.1038/s41467-024-47730-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Accepted: 04/10/2024] [Indexed: 04/25/2024] Open
Abstract
Topological spin textures are characterized by magnetic topological charges, Q, which govern their electromagnetic properties. Recent studies have achieved skyrmion bundles with arbitrary integer values of Q, opening possibilities for exploring topological spintronics based on Q. However, the realization of stable skyrmion bundles in chiral magnets at room temperature and zero magnetic field - the prerequisite for realistic device applications - has remained elusive. Here, through the combination of pulsed currents and reversed magnetic fields, we experimentally achieve skyrmion bundles with different integer Q values - reaching a maximum of 24 at above room temperature and zero magnetic field - in the chiral magnet Co8Zn10Mn2. We demonstrate the field-driven annihilation of high-Q bundles and present a phase diagram as a function of temperature and field. Our experimental findings are consistently corroborated by micromagnetic simulations, which reveal the nature of the skyrmion bundle as that of skyrmion tubes encircled by a fractional Hopfion.
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Grants
- This work was supported by the National Key R&D Program of China, Grant No. 2022YFA1403603 (H.D.); the Natural Science Foundation of China, Grants No. 12174396 (J.T.), 12104123 (Y.W.), and 12241406 (H.D.); the National Natural Science Funds for Distinguished Young Scholar, Grant No. 52325105 (H.D.); the Anhui Provincial Natural Science Foundation, Grant No. 2308085Y32 (J.T.); the Natural Science Project of Colleges and Universities in Anhui Province, Grant No. 2022AH030011 (J.T.); the Strategic Priority Research Program of Chinese Academy of Sciences, Grant No. XDB33030100 (H.D.); CAS Project for Young Scientists in Basic Research, Grant No. YSBR-084 (H.D.); Systematic Fundamental Research Program Leveraging Major Scientific and Technological Infrastructure, Chinese Academy of Sciences, Grant No. JZHKYPT-2021-08 (H.D.);Anhui Province Excellent Young Teacher Training Project Grant No. YQZD2023067 (Y.W.); and the China Postdoctoral Science Foundation Grant No. 2023M743543 (Y.W.).
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Affiliation(s)
- Yongsen Zhang
- Science Island Branch, Graduate School of USTC, Hefei, 230026, China
- Anhui Province Key Laboratory of Low-Energy Quantum Materials and Devices, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei, 230031, China
| | - Jin Tang
- School of Physics and Optoelectronic Engineering, Anhui University, Hefei, 230601, China.
| | - Yaodong Wu
- School of Physics and Materials Engineering, Hefei Normal University, Hefei, 230601, China
| | - Meng Shi
- Science Island Branch, Graduate School of USTC, Hefei, 230026, China
- Anhui Province Key Laboratory of Low-Energy Quantum Materials and Devices, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei, 230031, China
| | - Xitong Xu
- Anhui Province Key Laboratory of Low-Energy Quantum Materials and Devices, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei, 230031, China
| | - Shouguo Wang
- Anhui Key Laboratory of Magnetic Functional Materials and Devices, School of Materials Science and Engineering, Anhui University, Hefei, 230601, China
| | - Mingliang Tian
- Anhui Province Key Laboratory of Low-Energy Quantum Materials and Devices, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei, 230031, China
- School of Physics and Optoelectronic Engineering, Anhui University, Hefei, 230601, China
| | - Haifeng Du
- Anhui Province Key Laboratory of Low-Energy Quantum Materials and Devices, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei, 230031, China.
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3
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Kong JF, Ren Y, Tey MSN, Ho P, Khoo KH, Chen X, Soumyanarayanan A. Quantifying the Magnetic Interactions Governing Chiral Spin Textures Using Deep Neural Networks. ACS APPLIED MATERIALS & INTERFACES 2024; 16:1025-1032. [PMID: 38156820 DOI: 10.1021/acsami.3c12655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
The interplay of magnetic interactions in chiral multilayer films gives rise to nanoscale topological spin textures that form attractive elements for next-generation computing. Quantifying these interactions requires several specialized, time-consuming, and resource-intensive experimental techniques. Imaging of ambient domain configurations presents a promising avenue for high-throughput extraction of parent magnetic interactions. Here, we present a machine learning (ML)-based approach to simultaneously determine the key magnetic interactions─symmetric exchange, chiral exchange, and anisotropy─governing the chiral domain phenomenology in multilayers, using a single binarized image of domain configurations. Our convolutional neural network model, trained and validated on over 10,000 domain images, achieved R2 > 0.85 in predicting the parameters and independently learned the physical interdependencies between magnetic parameters. When applied to microscopy data acquired across samples, our model-predicted parameter trends are consistent with those of independent experimental measurements. These results establish ML-driven techniques as valuable, high-throughput complements to conventional determination of magnetic interactions and serve to accelerate materials and device development for nanoscale electronics.
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Affiliation(s)
- Jian Feng Kong
- Agency for Science, Technology & Research (A*STAR), Institute of High Performance Computing, Singapore 138632, Singapore
| | - Yuhua Ren
- Department of Physics, National University of Singapore, Singapore 117551, Singapore
| | - M S Nicholas Tey
- Agency for Science, Technology & Research (A*STAR), Institute of Materials Research & Engineering, Singapore 138634, Singapore
| | - Pin Ho
- Agency for Science, Technology & Research (A*STAR), Institute of Materials Research & Engineering, Singapore 138634, Singapore
| | - Khoong Hong Khoo
- Agency for Science, Technology & Research (A*STAR), Institute of High Performance Computing, Singapore 138632, Singapore
| | - Xiaoye Chen
- Agency for Science, Technology & Research (A*STAR), Institute of Materials Research & Engineering, Singapore 138634, Singapore
| | - Anjan Soumyanarayanan
- Department of Physics, National University of Singapore, Singapore 117551, Singapore
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4
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He B, Tomasello R, Luo X, Zhang R, Nie Z, Carpentieri M, Han X, Finocchio G, Yu G. All-Electrical 9-Bit Skyrmion-Based Racetrack Memory Designed with Laser Irradiation. NANO LETTERS 2023; 23:9482-9490. [PMID: 37818857 DOI: 10.1021/acs.nanolett.3c02978] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
Racetrack memories with magnetic skyrmions have recently been proposed as a promising storage technology. To be appealing, several challenges must still be faced for the deterministic generation of skyrmions, their high-fidelity transfer, and accurate reading. Here, we realize the first proof-of-concept of a 9-bit skyrmion racetrack memory with all-electrical controllable functionalities implemented in the same device. The key ingredient is the generation of a tailored nonuniform distribution of magnetic anisotropy via laser irradiation in order to (i) create a well-defined skyrmion nucleation center, (ii) define the memory cells hosting the information coded as the presence/absence of skyrmions, and (iii) improve the signal-to-noise ratio of anomalous Hall resistance measurements. This work introduces a strategy to unify previous findings and predictions for the development of a generation of racetrack memories with robust control of skyrmion nucleation and position, as well as effective skyrmion electrical detection.
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Affiliation(s)
- Bin He
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Riccardo Tomasello
- Department of Electrical and Information Engineering, Politecnico of Bari, Bari 70125, Italy
| | - Xuming Luo
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Ran Zhang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Zhuyang Nie
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Mario Carpentieri
- Department of Electrical and Information Engineering, Politecnico of Bari, Bari 70125, Italy
| | - Xiufeng Han
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, People's Republic of China
| | - Giovanni Finocchio
- Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, Messina 98166, Italy
| | - Guoqiang Yu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, People's Republic of China
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5
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Castell-Queralt J, Abad-López G, González-Gómez L, Del-Valle N, Navau C. Survival of skyrmions along granular racetracks at room temperature. NANOSCALE ADVANCES 2023; 5:4728-4734. [PMID: 37705781 PMCID: PMC10496888 DOI: 10.1039/d3na00464c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 07/27/2023] [Indexed: 09/15/2023]
Abstract
Skyrmions can be envisioned as bits of information that can be transported along nanoracetracks. However, temperature, defects, and/or granularity can produce diffusion, pinning, and, in general, modification in their dynamics. These effects may cause undesired errors in information transport. We present simulations of a realistic system where both the (room) temperature and sample granularity are taken into account. Key feasibility magnitudes, such as the success probability of a skyrmion traveling a given distance along the racetrack, are calculated. The results are evaluated in terms of the eventual loss of skyrmions by pinning, destruction at the edges, or excessive delay due to granularity. The model proposed is based on the Fokker-Planck equation resulting from Thiele's rigid model for skyrmions. The results could serve to establish error detection criteria and, in general, to discern the dynamics of skyrmions in realistic situations.
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Affiliation(s)
- Josep Castell-Queralt
- Departament de Física, Universitat Autònoma de Barcelona 08193 Bellaterra Barcelona Catalonia Spain
| | - Guillermo Abad-López
- Departament de Física, Universitat Autònoma de Barcelona 08193 Bellaterra Barcelona Catalonia Spain
| | - Leonardo González-Gómez
- Departament de Física, Universitat Autònoma de Barcelona 08193 Bellaterra Barcelona Catalonia Spain
| | - Nuria Del-Valle
- Departament de Física, Universitat Autònoma de Barcelona 08193 Bellaterra Barcelona Catalonia Spain
| | - Carles Navau
- Departament de Física, Universitat Autònoma de Barcelona 08193 Bellaterra Barcelona Catalonia Spain
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6
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Gisbert VG, Garcia R. Insights and guidelines to interpret forces and deformations at the nanoscale by using a tapping mode AFM simulator: dForce 2.0. SOFT MATTER 2023; 19:5857-5868. [PMID: 37305960 DOI: 10.1039/d3sm00334e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Amplitude modulation (tapping mode) AFM is the most versatile AFM mode for imaging surfaces at the nanoscale in air and liquid environments. However, it remains challenging to estimate the forces and deformations exerted by the tip. We introduce a new simulator environment to predict the values of the observables in tapping mode AFM experiments. The relevant feature of dForce 2.0 is the incorporation of contact mechanics models aimed to describe the properties of ultrathin samples. These models were essential to determine the forces applied on samples such as proteins, self-assembled monolayers, lipid bilayers, and few-layered materials. The simulator incorporates two types of long-range magnetic forces. The simulator is written in an open-source code (Python) and it can be run from a personal computer.
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Affiliation(s)
- Victor G Gisbert
- Instituto de Ciencia de Materiales de Madrid, CSIC c/Sor Juana Inés de la Cruz 3, 28049 Madrid, Spain.
| | - Ricardo Garcia
- Instituto de Ciencia de Materiales de Madrid, CSIC c/Sor Juana Inés de la Cruz 3, 28049 Madrid, Spain.
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7
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Volkov OM, Wolf D, Pylypovskyi OV, Kákay A, Sheka DD, Büchner B, Fassbender J, Lubk A, Makarov D. Chirality coupling in topological magnetic textures with multiple magnetochiral parameters. Nat Commun 2023; 14:1491. [PMID: 36932066 PMCID: PMC10023801 DOI: 10.1038/s41467-023-37081-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 03/01/2023] [Indexed: 03/19/2023] Open
Abstract
Chiral effects originate from the lack of inversion symmetry within the lattice unit cell or sample's shape. Being mapped onto magnetic ordering, chirality enables topologically non-trivial textures with a given handedness. Here, we demonstrate the existence of a static 3D texture characterized by two magnetochiral parameters being magnetic helicity of the vortex and geometrical chirality of the core string itself in geometrically curved asymmetric permalloy cap with a size of 80 nm and a vortex ground state. We experimentally validate the nonlocal chiral symmetry breaking effect in this object, which leads to the geometric deformation of the vortex string into a helix with curvature 3 μm-1 and torsion 11 μm-1. The geometric chirality of the vortex string is determined by the magnetic helicity of the vortex texture, constituting coupling of two chiral parameters within the same texture. Beyond the vortex state, we anticipate that complex curvilinear objects hosting 3D magnetic textures like curved skyrmion tubes and hopfions can be characterized by multiple coupled magnetochiral parameters, that influence their statics and field- or current-driven dynamics for spin-orbitronics and magnonics.
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Affiliation(s)
- Oleksii M Volkov
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Ion Beam Physics and Materials Research, Bautzner Landstr. 400, 01328, Dresden, Germany.
| | - Daniel Wolf
- Institute for Solid State Research, IFW Dresden, 01069, Dresden, Germany.
| | - Oleksandr V Pylypovskyi
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Ion Beam Physics and Materials Research, Bautzner Landstr. 400, 01328, Dresden, Germany.,Kyiv Academic University, 03142, Kyiv, Ukraine
| | - Attila Kákay
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Ion Beam Physics and Materials Research, Bautzner Landstr. 400, 01328, Dresden, Germany
| | - Denis D Sheka
- Taras Shevchenko National University of Kyiv, 01601, Kyiv, Ukraine
| | - Bernd Büchner
- Institute for Solid State Research, IFW Dresden, 01069, Dresden, Germany.,Institute of Solid State and Materials Physics, TU Dresden, 01069, Dresden, Germany.,Würzburg-Dresden Cluster of Excellence ct.qmat, Dresden, Germany
| | - Jürgen Fassbender
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Ion Beam Physics and Materials Research, Bautzner Landstr. 400, 01328, Dresden, Germany
| | - Axel Lubk
- Institute for Solid State Research, IFW Dresden, 01069, Dresden, Germany.,Institute of Solid State and Materials Physics, TU Dresden, 01069, Dresden, Germany.,Würzburg-Dresden Cluster of Excellence ct.qmat, Dresden, Germany
| | - Denys Makarov
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Ion Beam Physics and Materials Research, Bautzner Landstr. 400, 01328, Dresden, Germany.
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8
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Ahrens V, Kiesselbach C, Gnoli L, Giuliano D, Mendisch S, Kiechle M, Riente F, Becherer M. Skyrmions Under Control-FIB Irradiation as a Versatile Tool for Skyrmion Circuits. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2207321. [PMID: 36255142 DOI: 10.1002/adma.202207321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 10/11/2022] [Indexed: 06/16/2023]
Abstract
Magnetic data storage and processing offer certain advances over conventional technologies, amongst which nonvolatility and low power operation are the most outstanding ones. Skyrmions are a promising candidate as a magnetic data carrier. However, the sputtering of skyrmion films and the control of the skyrmion nucleation, motion, and annihilation remains challenging. This work demonstrates that using optimized focused ion beam irradiation and annealing protocols enables the skyrmion phase in W/CoFeB/MgO thin films to be accessed easily. By analyzing ion-beam-engineered skyrmion hosting wires, excited by sub-100 ns current pulses, possibilities to control skyrmion nucleation, guide their motion, and control their annihilation unfold. Overall, the key elements needed to develop extensive skyrmion networks are presented.
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Affiliation(s)
- Valentin Ahrens
- Department of Electrical and Computer Engineering, Technical University of Munich, 85748, Garching, Germany
| | - Clara Kiesselbach
- Department of Electrical and Computer Engineering, Technical University of Munich, 85748, Garching, Germany
| | - Luca Gnoli
- Department of Electronics and Telecommunications, Politecnico di Torino, Torino, 10129, Italy
| | - Domenico Giuliano
- Department of Electronics and Telecommunications, Politecnico di Torino, Torino, 10129, Italy
| | - Simon Mendisch
- Department of Electrical and Computer Engineering, Technical University of Munich, 85748, Garching, Germany
| | - Martina Kiechle
- Department of Electrical and Computer Engineering, Technical University of Munich, 85748, Garching, Germany
| | - Fabrizio Riente
- Department of Electronics and Telecommunications, Politecnico di Torino, Torino, 10129, Italy
| | - Markus Becherer
- Department of Electrical and Computer Engineering, Technical University of Munich, 85748, Garching, Germany
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9
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Powalla L, Birch MT, Litzius K, Wintz S, Schulz F, Weigand M, Scholz T, Lotsch BV, Kern K, Schütz G, Burghard M. Single Skyrmion Generation via a Vertical Nanocontact in a 2D Magnet-Based Heterostructure. NANO LETTERS 2022; 22:9236-9243. [PMID: 36400013 PMCID: PMC9756335 DOI: 10.1021/acs.nanolett.2c01944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 11/07/2022] [Indexed: 06/16/2023]
Abstract
Skyrmions have been well studied in chiral magnets and magnetic thin films due to their potential application in practical devices. Recently, monochiral skyrmions have been observed in two-dimensional van der Waals magnets. Their atomically flat surfaces and capability to be stacked into heterostructures offer new prospects for skyrmion applications. However, the controlled local nucleation of skyrmions within these materials has yet to be realized. Here, we utilize real-space X-ray microscopy to investigate a heterostructure composed of the 2D ferromagnet Fe3GeTe2 (FGT), an insulating hexagonal boron nitride layer, and a graphite top electrode. Upon a stepwise increase of the voltage applied between the graphite and FGT, a vertically conducting pathway can be formed. This nanocontact allows the tunable creation of individual skyrmions via single nanosecond pulses of low current density. Furthermore, time-resolved magnetic imaging highlights the stability of the nanocontact, while our micromagnetic simulations reproduce the observed skyrmion nucleation process.
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Affiliation(s)
- Lukas Powalla
- Max
Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569Stuttgart, Germany
| | - Max T. Birch
- Max
Planck Institute for Intelligent Systems, Heisenbergstrasse 3, D-70569Stuttgart, Germany
| | - Kai Litzius
- Max
Planck Institute for Intelligent Systems, Heisenbergstrasse 3, D-70569Stuttgart, Germany
| | - Sebastian Wintz
- Max
Planck Institute for Intelligent Systems, Heisenbergstrasse 3, D-70569Stuttgart, Germany
- Helmholtz-Zentrum
Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, D-14109Berlin, Germany
| | - Frank Schulz
- Max
Planck Institute for Intelligent Systems, Heisenbergstrasse 3, D-70569Stuttgart, Germany
| | - Markus Weigand
- Max
Planck Institute for Intelligent Systems, Heisenbergstrasse 3, D-70569Stuttgart, Germany
- Helmholtz-Zentrum
Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, D-14109Berlin, Germany
| | - Tanja Scholz
- Max
Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569Stuttgart, Germany
| | - Bettina V. Lotsch
- Max
Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569Stuttgart, Germany
- University
of Munich (LMU), Butenandtstraße 5-13 (Haus D), 81377München, Germany
| | - Klaus Kern
- Max
Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569Stuttgart, Germany
- Institute
de Physique, École Polytechnique
Fédérale de Lausanne, CH-1015Lausanne, Switzerland
| | - Gisela Schütz
- Max
Planck Institute for Intelligent Systems, Heisenbergstrasse 3, D-70569Stuttgart, Germany
| | - Marko Burghard
- Max
Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569Stuttgart, Germany
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10
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Zhao X, Tang J, Pei K, Wang W, Lin SZ, Du H, Tian M, Che R. Current-Induced Magnetic Skyrmions with Controllable Polarities in the Helical Phase. NANO LETTERS 2022; 22:8793-8800. [PMID: 36331209 DOI: 10.1021/acs.nanolett.2c02061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
We report the current-induced creation of magnetic skyrmions in a chiral magnet FeGe nanostructure by using in situ Lorentz transmission electron microscopy. We show that magnetic skyrmions with controllable polarity can be transferred from the helical ground state simply by controlling the direction of the current flow at zero magnetic fields. The force analysis and symmetry consideration, backed up by micromagnetic simulations, well explain the experimental results, where magnetic skyrmions are created because of the edge instability of the helical state in the presence of spin-transfer torque. The on-demand generation of skyrmions and control of their polarity by electric current without the need for a magnetic field will enable novel purely electric-controlled skyrmion devices.
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Affiliation(s)
- Xuebing Zhao
- Laboratory of Advanced Materials, Shanghai Key Lab of Molecular Catalysis and Innovative Materials, Department of Materials Science, Fudan University, Shanghai200438, China
| | - Jin Tang
- School of Physics and Optoelectronics Engineering Science, Anhui University, Hefei230601, China
- Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei230031, China
| | - Ke Pei
- Laboratory of Advanced Materials, Shanghai Key Lab of Molecular Catalysis and Innovative Materials, Department of Materials Science, Fudan University, Shanghai200438, China
| | - Weiwei Wang
- School of Physics and Optoelectronics Engineering Science, Anhui University, Hefei230601, China
| | - Shi-Zeng Lin
- Theoretical Division and Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico87545, United States
| | - Haifeng Du
- School of Physics and Optoelectronics Engineering Science, Anhui University, Hefei230601, China
- Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei230031, China
| | - Mingliang Tian
- School of Physics and Optoelectronics Engineering Science, Anhui University, Hefei230601, China
- Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei230031, China
| | - Renchao Che
- Laboratory of Advanced Materials, Shanghai Key Lab of Molecular Catalysis and Innovative Materials, Department of Materials Science, Fudan University, Shanghai200438, China
- Zhejiang Laboratory, Hangzhou311100, China
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11
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Cubukcu M, Pöllath S, Tacchi S, Stacey A, Darwin E, Freeman CWF, Barton C, Hickey BJ, Marrows CH, Carlotti G, Back CH, Kazakova O. Manipulation of Magnetic Skyrmion Density in Continuous Ir/Co/Pt Multilayers. MICROMACHINES 2022; 13:1911. [PMID: 36363931 PMCID: PMC9693305 DOI: 10.3390/mi13111911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 10/27/2022] [Accepted: 11/02/2022] [Indexed: 06/16/2023]
Abstract
We show that magnetic skyrmions can be stabilised at room temperature in continuous [Ir/Co/Pt]5 multilayers on SiO2/Si substrates without the prior application of electric current or magnetic field. While decreasing the Co thickness, a transition of the magnetic domain patterns from worm-like state to separated stripes is observed. The skyrmions are clearly imaged in both states using magnetic force microscopy. The density of skyrmions can be significantly enhanced after applying the "in-plane field procedure". Our results provide means to manipulate magnetic skyrmion density, further allowing for the optimised engineering of skyrmion-based devices.
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Affiliation(s)
- M. Cubukcu
- National Physical Laboratory, Teddington TW11 0LW, UK
- London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London WC1H 0AH, UK
| | - S. Pöllath
- Institut für Experimentelle Physik, Universität Regensburg, D-93040 Regensburg, Germany
| | - S. Tacchi
- Istituto Officina dei Materiali del CNR (CNR-IOM), Sede Secondaria di Perugia, c/o Dipartimento di Fisica e Geologia, Università di Perugia, I-06123 Perugia, Italy
| | - A. Stacey
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
| | - E. Darwin
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
| | - C. W. F. Freeman
- National Physical Laboratory, Teddington TW11 0LW, UK
- London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London WC1H 0AH, UK
| | - C. Barton
- National Physical Laboratory, Teddington TW11 0LW, UK
| | - B. J. Hickey
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
| | - C. H. Marrows
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
| | - G. Carlotti
- Dipartimento di Fisica e Geologia, Università di Perugia, Via Pascoli, I-06123 Perugia, Italy
| | - C. H. Back
- Physik-Department, Technical University Munich, 85748 Garching, Germany
| | - O. Kazakova
- National Physical Laboratory, Teddington TW11 0LW, UK
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12
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Yokouchi T, Sugimoto S, Rana B, Seki S, Ogawa N, Shiomi Y, Kasai S, Otani Y. Pattern recognition with neuromorphic computing using magnetic field-induced dynamics of skyrmions. SCIENCE ADVANCES 2022; 8:eabq5652. [PMID: 36179033 PMCID: PMC9524829 DOI: 10.1126/sciadv.abq5652] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Accepted: 08/15/2022] [Indexed: 06/12/2023]
Abstract
Nonlinear phenomena in physical systems can be used for brain-inspired computing with low energy consumption. Response from the dynamics of a topological spin structure called skyrmion is one of the candidates for such a neuromorphic computing. However, its ability has not been well explored experimentally. Here, we experimentally demonstrate neuromorphic computing using nonlinear response originating from magnetic field-induced dynamics of skyrmions. We designed a simple-structured skyrmion-based neuromorphic device and succeeded in handwritten digit recognition with the accuracy as large as 94.7% and waveform recognition. Notably, there exists a positive correlation between the recognition accuracy and the number of skyrmions in the devices. The large degrees of freedom of skyrmion systems, such as the position and the size, originate from the more complex nonlinear mapping, the larger output dimension, and, thus, high accuracy. Our results provide a guideline for developing energy-saving and high-performance skyrmion neuromorphic computing devices.
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Affiliation(s)
- Tomoyuki Yokouchi
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
- Department of Basic Science, The University of Tokyo, Tokyo 152-8902, Japan
| | - Satoshi Sugimoto
- National Institute for Materials Science (NIMS), Tsukuba 305-0047, Japan
| | - Bivas Rana
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
- Institute of Spintronics and Quantum Information, Faculty of Physics, Adam Mickiewicz University, Poznań, Uniwersytetu Poznanskiego 2, Poznań 61-614, Poland
| | - Shinichiro Seki
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
- PRESTO, Japan Science and Technology Agency (JST), Tokyo 102-0075, Japan
- Department of Applied Physics, The University of Tokyo, Tokyo 113-8656, Japan
- Institute of Engineering Innovation, The University of Tokyo, Tokyo 113-8656, Japan
| | - Naoki Ogawa
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
- PRESTO, Japan Science and Technology Agency (JST), Tokyo 102-0075, Japan
- Department of Applied Physics, The University of Tokyo, Tokyo 113-8656, Japan
| | - Yuki Shiomi
- Department of Basic Science, The University of Tokyo, Tokyo 152-8902, Japan
| | - Shinya Kasai
- National Institute for Materials Science (NIMS), Tsukuba 305-0047, Japan
- PRESTO, Japan Science and Technology Agency (JST), Tokyo 102-0075, Japan
| | - Yoshichika Otani
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
- Institute for Solid State Physics (ISSP), The University of Tokyo, Kashiwa 277-8561, Japan
- Trans-scale Quantum Science Institute, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
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13
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Zhu R, Jiang Z, Zhang X, Zhong X, Tan C, Liu M, Sun Y, Li X, Qi R, Qu K, Liu Z, Wu M, Li M, Huang B, Xu Z, Wang J, Liu K, Gao P, Wang J, Li J, Bai X. Dynamics of Polar Skyrmion Bubbles under Electric Fields. PHYSICAL REVIEW LETTERS 2022; 129:107601. [PMID: 36112449 DOI: 10.1103/physrevlett.129.107601] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 06/23/2022] [Accepted: 08/11/2022] [Indexed: 06/15/2023]
Abstract
Room-temperature polar skyrmions, which have been recently discovered in oxide superlattice, have received considerable attention for their potential applications in nanoelectronics owing to their nanometer size, emergent chirality, and negative capacitance. For practical applications, their manipulation using external stimuli is a prerequisite. Herein, we study the dynamics of individual polar skyrmions at the nanoscale via in situ scanning transmission electron microscopy. By monitoring the electric-field-driven creation, annihilation, shrinkage, and expansion of topological structures in real space, we demonstrate the reversible transformation among skyrmion bubbles, elongated skyrmions, and monodomains. The underlying mechanism and interactions are discussed in conjunction with phase-field simulations. The electrical manipulation of nanoscale polar skyrmions allows the tuning of their dielectric permittivity at the atomic scale, and the detailed knowledge of their phase transition behaviors provides fundamentals for their applications in nanoelectronics.
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Affiliation(s)
- Ruixue Zhu
- Electron Microscopy Laboratory and International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Zhexin Jiang
- Department of Engineering Mechanics, Zhejiang University, Hangzhou 310027, Zhejiang, China
| | - Xinxin Zhang
- Electron Microscopy Laboratory and International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Xiangli Zhong
- School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105, Hunan, China
| | - Congbing Tan
- Hunan Provincial Key Laboratory of Intelligent Sensors and Advanced Sensor Materials, School of Physics and Electronics, Hunan University of Science and Technology, Xiangtan 411201, Hunan, China
| | - Mingwei Liu
- Hunan Provincial Key Laboratory of Intelligent Sensors and Advanced Sensor Materials, School of Physics and Electronics, Hunan University of Science and Technology, Xiangtan 411201, Hunan, China
| | - Yuanwei Sun
- Electron Microscopy Laboratory and International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Xiaomei Li
- Electron Microscopy Laboratory and International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Ruishi Qi
- Electron Microscopy Laboratory and International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Ke Qu
- Electron Microscopy Laboratory and International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Zhetong Liu
- Electron Microscopy Laboratory and International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Mei Wu
- Electron Microscopy Laboratory and International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Mingqiang Li
- Electron Microscopy Laboratory and International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Boyuan Huang
- Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, Guangdong, China
| | - Zhi Xu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Jinbin Wang
- School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105, Hunan, China
| | - Kaihui Liu
- State Key Laboratory for Artificial Microstructure & Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
- Interdisciplinary Institute of Light-Element Quantum Materials and Research Center for Light-Element Advanced Materials, Peking University, Beijing, 100871, China
| | - Peng Gao
- Electron Microscopy Laboratory and International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Interdisciplinary Institute of Light-Element Quantum Materials and Research Center for Light-Element Advanced Materials, Peking University, Beijing, 100871, China
| | - Jie Wang
- Department of Engineering Mechanics, Zhejiang University, Hangzhou 310027, Zhejiang, China
- Zhejiang Laboratory, Hangzhou 311100, Zhejiang, China
| | - Jiangyu Li
- Guangdong Provincial Key Laboratory of Functional Oxide Materials and Devices, Southern University of Science and Technology, Shenzhen 518055, Guangdong, China
| | - Xuedong Bai
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
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14
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Quessab Y, Xu JW, Cogulu E, Finizio S, Raabe J, Kent AD. Zero-Field Nucleation and Fast Motion of Skyrmions Induced by Nanosecond Current Pulses in a Ferrimagnetic Thin Film. NANO LETTERS 2022; 22:6091-6097. [PMID: 35877983 DOI: 10.1021/acs.nanolett.2c01038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Skyrmion racetrack memories are highly attractive for next-generation data storage technologies. Skyrmions are noncollinear spin textures stabilized by chiral interactions. To achieve a fast-operating memory device, it is critical to move skyrmions at high speeds. The skyrmion dynamics induced by spin-orbit torques (SOTs) in the commonly studied ferromagnetic films is hindered by strong pinning effects and a large skyrmion Hall effect causing deflection of the skyrmion toward the racetrack edge, which can lead to information loss. Here, we investigate the current-induced nucleation and motion of skyrmions in ferrimagnetic Pt/CoGd/(W or Ta) thin films. We first reveal field-free skyrmion nucleation mediated by Joule heating. We then achieve fast skyrmion motion driven by SOTs with velocities as high as 610 m s-1 and a small skyrmion Hall angle |θSkHE| ≲ 3°. Our results show that ferrimagnets are better candidates for fast skyrmion-based memory devices with low risk of information loss.
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Affiliation(s)
- Yassine Quessab
- Center for Quantum Phenomena, Department of Physics, New York University, New York, New York, 10003, United States
| | - Jun-Wen Xu
- Center for Quantum Phenomena, Department of Physics, New York University, New York, New York, 10003, United States
| | - Egecan Cogulu
- Center for Quantum Phenomena, Department of Physics, New York University, New York, New York, 10003, United States
| | - Simone Finizio
- Swiss Light Source, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Jörg Raabe
- Swiss Light Source, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Andrew D Kent
- Center for Quantum Phenomena, Department of Physics, New York University, New York, New York, 10003, United States
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15
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Vélez S, Ruiz-Gómez S, Schaab J, Gradauskaite E, Wörnle MS, Welter P, Jacot BJ, Degen CL, Trassin M, Fiebig M, Gambardella P. Current-driven dynamics and ratchet effect of skyrmion bubbles in a ferrimagnetic insulator. NATURE NANOTECHNOLOGY 2022; 17:834-841. [PMID: 35788187 DOI: 10.1038/s41565-022-01144-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 05/02/2022] [Indexed: 06/15/2023]
Abstract
Magnetic skyrmions are compact chiral spin textures that exhibit a rich variety of topological phenomena and hold potential for the development of high-density memory devices and novel computing schemes driven by spin currents. Here, we demonstrate the room-temperature interfacial stabilization and current-driven control of skyrmion bubbles in the ferrimagnetic insulator Tm3Fe5O12 coupled to Pt, showing the current-induced motion of individual skyrmion bubbles. The ferrimagnetic order of the crystal together with the interplay of spin-orbit torques and pinning determine the skyrmion dynamics in Tm3Fe5O12 and result in a strong skyrmion Hall effect characterized by a negative deflection angle and hopping motion. Further, we show that the velocity and depinning threshold of the skyrmion bubbles can be modified by exchange coupling Tm3Fe5O12 to an in-plane magnetized Y3Fe5O12 layer, which distorts the spin texture of the skyrmions and leads to directional-dependent rectification of their dynamics. This effect, which is equivalent to a magnetic ratchet, is exploited to control the skyrmion flow in a racetrack-like device.
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Affiliation(s)
- Saül Vélez
- Department of Materials, ETH Zurich, Zurich, Switzerland.
- Condensed Matter Physics Center, Instituto Nicolás Cabrera, and Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, Madrid, Spain.
| | - Sandra Ruiz-Gómez
- Departamento de Física de Materiales, Universidad Complutense de Madrid, Madrid, Spain
- Alba Synchrotron Light Facility, Barcelona, Spain
- Max Planck Institute for Chemical Physics of Solids, Dresden, Germany
| | - Jakob Schaab
- Department of Materials, ETH Zurich, Zurich, Switzerland
| | | | | | - Pol Welter
- Department of Physics, ETH Zurich, Zurich, Switzerland
| | | | | | - Morgan Trassin
- Department of Materials, ETH Zurich, Zurich, Switzerland
| | - Manfred Fiebig
- Department of Materials, ETH Zurich, Zurich, Switzerland
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16
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MacKinnon CR, Zeissler K, Finizio S, Raabe J, Marrows CH, Mercer T, Bissell PR, Lepadatu S. Collective skyrmion motion under the influence of an additional interfacial spin-transfer torque. Sci Rep 2022; 12:10786. [PMID: 35750744 PMCID: PMC9232533 DOI: 10.1038/s41598-022-14969-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 06/15/2022] [Indexed: 11/26/2022] Open
Abstract
Here we study the effect of an additional interfacial spin-transfer torque, as well as the well-established spin–orbit torque and bulk spin-transfer torque, on skyrmion collections—group of skyrmions dense enough that they are not isolated from one another—in ultrathin heavy metal/ferromagnetic multilayers, by comparing modelling with experimental results. Using a skyrmion collection with a range of skyrmion diameters and landscape disorder, we study the dependence of the skyrmion Hall angle on diameter and velocity, as well as the velocity as a function of diameter. We show that inclusion of the interfacial spin-transfer torque results in reduced skyrmion Hall angles, with values close to experimental results. We also show that for skyrmion collections the velocity is approximately independent of diameter, in marked contrast to the motion of isolated skyrmions, as the group of skyrmions move together at an average group velocity. Moreover, the calculated skyrmion velocities are comparable to those obtained in experiments when the interfacial spin-transfer torque is included. Our results thus show the significance of the interfacial spin-transfer torque in ultrathin magnetic multilayers, which helps to explain the low skyrmion Hall angles and velocities observed in experiment. We conclude that the interfacial spin-transfer torque should be considered in numerical modelling for reproduction of experimental results.
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Affiliation(s)
- Callum R MacKinnon
- Jeremiah Horrocks Institute for Mathematics, Physics and Astronomy, University of Central Lancashire, Preston, PR1 2HE, UK.
| | - Katharina Zeissler
- School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK.,Bragg Center for Materials Research, University of Leeds, Leeds, LS2 9JT, UK
| | - Simone Finizio
- Swiss Light Source, Paul Scherrer Institut, 5232, Villigen, Switzerland
| | - Jörg Raabe
- Swiss Light Source, Paul Scherrer Institut, 5232, Villigen, Switzerland
| | - Christopher H Marrows
- School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK.,Bragg Center for Materials Research, University of Leeds, Leeds, LS2 9JT, UK
| | - Tim Mercer
- Jeremiah Horrocks Institute for Mathematics, Physics and Astronomy, University of Central Lancashire, Preston, PR1 2HE, UK
| | - Philip R Bissell
- Jeremiah Horrocks Institute for Mathematics, Physics and Astronomy, University of Central Lancashire, Preston, PR1 2HE, UK
| | - Serban Lepadatu
- Jeremiah Horrocks Institute for Mathematics, Physics and Astronomy, University of Central Lancashire, Preston, PR1 2HE, UK.
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17
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Asymmetric Motion of Magnetic Skyrmions in Ferromagnetic Nanotubes Induced by a Magnetic Field. Symmetry (Basel) 2022. [DOI: 10.3390/sym14061195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Magnetic skyrmions, featuring topological stability and low driving current density, are believed to be a promising candidate of information carriers. One of the obstacles to application is the skyrmion Hall effect, which can lead to the annihilation of moving skyrmions at the lateral boundary of thin-film tracks. In order to resolve this issue, it was recently proposed to exploit ferromagnetic nanotubes as alternative skyrmion guides. In this work, we investigate the field-effect of current-driven skyrmion motion in nanotubes using micromagnetic simulations. It is found that, in the presence of an axial field, the skyrmion motion becomes asymmetric in tubes. This is fundamentally different from the flat strip, in which a field has little influence on the skyrmion dynamics. Based on the dissipation tensor determined by the spin texture of the skyrmions, the solution of the Thiele equation is obtained, yielding a perfect match with simulations. We argue that the asymmetry of the skyrmion dynamics originates from the curvature of the nanotube.
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18
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Abstract
A key issue for skyrmion dynamics and devices are pinning effects present in real systems. While posing a challenge for the realization of conventional skyrmionics devices, exploiting pinning effects can enable non-conventional computing approaches if the details of the pinning in real samples are quantified and understood. We demonstrate that using thermal skyrmion dynamics, we can characterize the pinning of a sample and we ascertain the spatially resolved energy landscape. To understand the mechanism of the pinning, we probe the strong skyrmion size and shape dependence of the pinning. Magnetic microscopy imaging demonstrates that in contrast to findings in previous investigations, for large skyrmions the pinning originates at the skyrmion boundary and not at its core. The boundary pinning is strongly influenced by the very complex pinning energy landscape that goes beyond the conventional effective rigid quasi-particle description. This gives rise to complex skyrmion shape distortions and allows for dynamic switching of pinning sites and flexible tuning of the pinning. Skyrmions, topological spin textures, can be pinned by defects present in the material that hosts them, influencing their motion. Here, Gruber et al show that the skyrmions are pinned at their boundary where the finite size of the skyrmions governs their pinning, and they demonstrate that certain pinning sites can switched on and off in-situ.
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19
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Abstract
A generic theory about skyrmion crystal (SkX) formation in chiral magnetic thin films and its fascinating thermodynamic behaviours is presented. A chiral magnetic film can have many metastable states with an arbitrary skyrmion density up to a maximal value when the parameter κ, which measures the relative Dzyaloshinskii-Moriya interaction (DMI) strength, is large enough. The lowest energy state of an infinite film is a long zig-zag ramified stripe skyrmion occupying the whole film in the absence of a magnetic field. Under an intermediate field perpendicular to the film, the lowest energy state has a finite skyrmion density. This is why a chiral magnetic film is often in a stripy state at a low field and a SkX only around an optimal field when κ is above a critical value. The lowest energy state is still a stripy helical state no matter with or without a field when κ is below the critical value. The multi-metastable states explain the thermodynamic path dependences of the various metastable states of a film. The decrease of the κ value with the temperature explains why SkXs become metastable at low temperatures in many skyrmion systems. These findings open a new avenue for SkX manipulation and skyrmion-based applications.
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Affiliation(s)
- Xu-Chong Hu
- Physics Department, The Hong Kong University of Science and Technology (HKUST), Clear Water Bay, Kowloon, Hong Kong.
- HKUST Shenzhen Research Institute, Shenzhen 518057, China
| | - Hai-Tao Wu
- Physics Department, The Hong Kong University of Science and Technology (HKUST), Clear Water Bay, Kowloon, Hong Kong.
- HKUST Shenzhen Research Institute, Shenzhen 518057, China
| | - X R Wang
- Physics Department, The Hong Kong University of Science and Technology (HKUST), Clear Water Bay, Kowloon, Hong Kong.
- HKUST Shenzhen Research Institute, Shenzhen 518057, China
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20
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Kern LM, Pfau B, Deinhart V, Schneider M, Klose C, Gerlinger K, Wittrock S, Engel D, Will I, Günther CM, Liefferink R, Mentink JH, Wintz S, Weigand M, Huang MJ, Battistelli R, Metternich D, Büttner F, Höflich K, Eisebitt S. Deterministic Generation and Guided Motion of Magnetic Skyrmions by Focused He +-Ion Irradiation. NANO LETTERS 2022; 22:4028-4035. [PMID: 35577328 PMCID: PMC9137908 DOI: 10.1021/acs.nanolett.2c00670] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 05/02/2022] [Indexed: 05/18/2023]
Abstract
Magnetic skyrmions are quasiparticles with nontrivial topology, envisioned to play a key role in next-generation data technology while simultaneously attracting fundamental research interest due to their emerging topological charge. In chiral magnetic multilayers, current-generated spin-orbit torques or ultrafast laser excitation can be used to nucleate isolated skyrmions on a picosecond time scale. Both methods, however, produce randomly arranged skyrmions, which inherently limits the precision on the location at which the skyrmions are nucleated. Here, we show that nanopatterning of the anisotropy landscape with a He+-ion beam creates well-defined skyrmion nucleation sites, thereby transforming the skyrmion localization into a deterministic process. This approach allows control of individual skyrmion nucleation as well as guided skyrmion motion with nanometer-scale precision, which is pivotal for both future fundamental studies of skyrmion dynamics and applications.
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Affiliation(s)
- Lisa-Marie Kern
- Max
Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, 12489 Berlin, Germany
| | - Bastian Pfau
- Max
Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, 12489 Berlin, Germany
- E-mail:
| | - Victor Deinhart
- Max
Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, 12489 Berlin, Germany
- Ferdinand-Braun-Institut
gGmbH, Leibniz-Institut für Höchstfrequenztechnik, 12489 Berlin, Germany
- Helmholtz-Zentrum
für Materialien und Energie GmbH, 14109 Berlin, Germany
| | - Michael Schneider
- Max
Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, 12489 Berlin, Germany
| | - Christopher Klose
- Max
Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, 12489 Berlin, Germany
| | - Kathinka Gerlinger
- Max
Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, 12489 Berlin, Germany
| | - Steffen Wittrock
- Max
Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, 12489 Berlin, Germany
| | - Dieter Engel
- Max
Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, 12489 Berlin, Germany
| | - Ingo Will
- Max
Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, 12489 Berlin, Germany
| | - Christian M. Günther
- Technische
Universität Berlin, Zentraleinrichtung Elektronenmikroskopie (ZELMI), 10623 Berlin, Germany
| | - Rein Liefferink
- Radboud
University, Institute for
Molecules and Materials (IMM), 6525 AJ Nijmegen, Netherlands
| | - Johan H. Mentink
- Radboud
University, Institute for
Molecules and Materials (IMM), 6525 AJ Nijmegen, Netherlands
| | - Sebastian Wintz
- Max
Planck Institute for Intelligent Systems, 70569 Stuttgart, Germany
| | - Markus Weigand
- Helmholtz-Zentrum
für Materialien und Energie GmbH, 14109 Berlin, Germany
| | - Meng-Jie Huang
- Deutsches
Elektronen-Synchrotron (DESY), 22607 Hamburg, Germany
| | | | - Daniel Metternich
- Helmholtz-Zentrum
für Materialien und Energie GmbH, 14109 Berlin, Germany
| | - Felix Büttner
- Helmholtz-Zentrum
für Materialien und Energie GmbH, 14109 Berlin, Germany
| | - Katja Höflich
- Ferdinand-Braun-Institut
gGmbH, Leibniz-Institut für Höchstfrequenztechnik, 12489 Berlin, Germany
- Helmholtz-Zentrum
für Materialien und Energie GmbH, 14109 Berlin, Germany
| | - Stefan Eisebitt
- Max
Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, 12489 Berlin, Germany
- Technische
Universität Berlin, Institut für
Optik und Atomare Physik, 10623 Berlin, Germany
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21
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Wang QH, Bedoya-Pinto A, Blei M, Dismukes AH, Hamo A, Jenkins S, Koperski M, Liu Y, Sun QC, Telford EJ, Kim HH, Augustin M, Vool U, Yin JX, Li LH, Falin A, Dean CR, Casanova F, Evans RFL, Chshiev M, Mishchenko A, Petrovic C, He R, Zhao L, Tsen AW, Gerardot BD, Brotons-Gisbert M, Guguchia Z, Roy X, Tongay S, Wang Z, Hasan MZ, Wrachtrup J, Yacoby A, Fert A, Parkin S, Novoselov KS, Dai P, Balicas L, Santos EJG. The Magnetic Genome of Two-Dimensional van der Waals Materials. ACS NANO 2022; 16:6960-7079. [PMID: 35442017 PMCID: PMC9134533 DOI: 10.1021/acsnano.1c09150] [Citation(s) in RCA: 54] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 02/23/2022] [Indexed: 05/23/2023]
Abstract
Magnetism in two-dimensional (2D) van der Waals (vdW) materials has recently emerged as one of the most promising areas in condensed matter research, with many exciting emerging properties and significant potential for applications ranging from topological magnonics to low-power spintronics, quantum computing, and optical communications. In the brief time after their discovery, 2D magnets have blossomed into a rich area for investigation, where fundamental concepts in magnetism are challenged by the behavior of spins that can develop at the single layer limit. However, much effort is still needed in multiple fronts before 2D magnets can be routinely used for practical implementations. In this comprehensive review, prominent authors with expertise in complementary fields of 2D magnetism (i.e., synthesis, device engineering, magneto-optics, imaging, transport, mechanics, spin excitations, and theory and simulations) have joined together to provide a genome of current knowledge and a guideline for future developments in 2D magnetic materials research.
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Affiliation(s)
- Qing Hua Wang
- Materials
Science and Engineering, School for Engineering of Matter, Transport
and Energy, Arizona State University, Tempe, Arizona 85287, United States
| | - Amilcar Bedoya-Pinto
- NISE
Department, Max Planck Institute of Microstructure
Physics, 06120 Halle, Germany
- Instituto
de Ciencia Molecular (ICMol), Universitat
de València, 46980 Paterna, Spain
| | - Mark Blei
- Materials
Science and Engineering, School for Engineering of Matter, Transport
and Energy, Arizona State University, Tempe, Arizona 85287, United States
| | - Avalon H. Dismukes
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Assaf Hamo
- Department
of Physics, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Sarah Jenkins
- Twist
Group,
Faculty of Physics, University of Duisburg-Essen, Campus Duisburg, 47057 Duisburg, Germany
| | - Maciej Koperski
- Institute
for Functional Intelligent Materials, National
University of Singapore, 117544 Singapore
| | - Yu Liu
- Condensed
Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Qi-Chao Sun
- Physikalisches
Institut, University of Stuttgart, 70569 Stuttgart, Germany
| | - Evan J. Telford
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
- Department
of Physics, Columbia University, New York, New York 10027, United States
| | - Hyun Ho Kim
- School
of Materials Science and Engineering, Department of Energy Engineering
Convergence, Kumoh National Institute of
Technology, Gumi 39177, Korea
| | - Mathias Augustin
- Institute
for Condensed Matter Physics and Complex Systems, School of Physics
and Astronomy, The University of Edinburgh, Edinburgh, EH9 3FD, United Kingdom
- Donostia
International Physics Center (DIPC), 20018 Donostia-San Sebastián, Basque Country, Spain
| | - Uri Vool
- Department
of Physics, Harvard University, Cambridge, Massachusetts 02138, United States
- John Harvard
Distinguished Science Fellows Program, Harvard
University, Cambridge, Massachusetts 02138, United States
| | - Jia-Xin Yin
- Laboratory
for Topological Quantum Matter and Spectroscopy, Department of Physics, Princeton University, Princeton, New Jersey 08544, United States
| | - Lu Hua Li
- Institute
for Frontier Materials, Deakin University, Geelong Waurn Ponds Campus, Waurn Ponds, Victoria 3216, Australia
| | - Alexey Falin
- Institute
for Frontier Materials, Deakin University, Geelong Waurn Ponds Campus, Waurn Ponds, Victoria 3216, Australia
| | - Cory R. Dean
- Department
of Physics, Columbia University, New York, New York 10027, United States
| | - Fèlix Casanova
- CIC nanoGUNE
BRTA, 20018 Donostia - San Sebastián, Basque
Country, Spain
- IKERBASQUE,
Basque Foundation for Science, 48013 Bilbao, Basque Country, Spain
| | - Richard F. L. Evans
- Department
of Physics, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Mairbek Chshiev
- Université
Grenoble Alpes, CEA, CNRS, Spintec, 38000 Grenoble, France
- Institut
Universitaire de France, 75231 Paris, France
| | - Artem Mishchenko
- Department
of Physics and Astronomy, University of
Manchester, Manchester, M13 9PL, United Kingdom
- National
Graphene Institute, University of Manchester, Manchester, M13 9PL, United Kingdom
| | - Cedomir Petrovic
- Condensed
Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Rui He
- Department
of Electrical and Computer Engineering, Texas Tech University, 910 Boston Avenue, Lubbock, Texas 79409, United
States
| | - Liuyan Zhao
- Department
of Physics, University of Michigan, 450 Church Street, Ann Arbor, Michigan 48109, United States
| | - Adam W. Tsen
- Institute
for Quantum Computing and Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Brian D. Gerardot
- SUPA, Institute
of Photonics and Quantum Sciences, Heriot-Watt
University, Edinburgh EH14 4AS, United Kingdom
| | - Mauro Brotons-Gisbert
- SUPA, Institute
of Photonics and Quantum Sciences, Heriot-Watt
University, Edinburgh EH14 4AS, United Kingdom
| | - Zurab Guguchia
- Laboratory
for Muon Spin Spectroscopy, Paul Scherrer
Institute, CH-5232 Villigen PSI, Switzerland
| | - Xavier Roy
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Sefaattin Tongay
- Materials
Science and Engineering, School for Engineering of Matter, Transport
and Energy, Arizona State University, Tempe, Arizona 85287, United States
| | - Ziwei Wang
- Department
of Physics and Astronomy, University of
Manchester, Manchester, M13 9PL, United Kingdom
- National
Graphene Institute, University of Manchester, Manchester, M13 9PL, United Kingdom
| | - M. Zahid Hasan
- Materials
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
- Princeton
Institute for Science and Technology of Materials, Princeton University, Princeton, New Jersey 08544, United States
- National
High Magnetic Field Laboratory, Florida
State University, Tallahassee, Florida 32310, United States
| | - Joerg Wrachtrup
- Physikalisches
Institut, University of Stuttgart, 70569 Stuttgart, Germany
- Max Planck
Institute for Solid State Research, 70569 Stuttgart, Germany
| | - Amir Yacoby
- Department
of Physics, Harvard University, Cambridge, Massachusetts 02138, United States
- John A.
Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Albert Fert
- Donostia
International Physics Center (DIPC), 20018 Donostia-San Sebastián, Basque Country, Spain
- Unité
Mixte de Physique, CNRS, Thales, Université Paris-Saclay, 91767 Palaiseau, France
- Department
of Materials Physics UPV/EHU, 20018 Donostia - San Sebastián, Basque Country, Spain
| | - Stuart Parkin
- NISE
Department, Max Planck Institute of Microstructure
Physics, 06120 Halle, Germany
| | - Kostya S. Novoselov
- Institute
for Functional Intelligent Materials, National
University of Singapore, 117544 Singapore
| | - Pengcheng Dai
- Department
of Physics and Astronomy, Rice University, Houston, Texas 77005, United States
| | - Luis Balicas
- National
High Magnetic Field Laboratory, Florida
State University, Tallahassee, Florida 32310, United States
- Department
of Physics, Florida State University, Tallahassee, Florida 32306, United States
| | - Elton J. G. Santos
- Institute
for Condensed Matter Physics and Complex Systems, School of Physics
and Astronomy, The University of Edinburgh, Edinburgh, EH9 3FD, United Kingdom
- Donostia
International Physics Center (DIPC), 20018 Donostia-San Sebastián, Basque Country, Spain
- Higgs Centre
for Theoretical Physics, The University
of Edinburgh, Edinburgh EH9 3FD, United Kingdom
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22
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Zhang H, Raftrey D, Chan YT, Shao YT, Chen R, Chen X, Huang X, Reichanadter JT, Dong K, Susarla S, Caretta L, Chen Z, Yao J, Fischer P, Neaton JB, Wu W, Muller DA, Birgeneau RJ, Ramesh R. Room-temperature skyrmion lattice in a layered magnet (Fe 0.5Co 0.5) 5GeTe 2. SCIENCE ADVANCES 2022; 8:eabm7103. [PMID: 35319983 PMCID: PMC8942374 DOI: 10.1126/sciadv.abm7103] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 01/28/2022] [Indexed: 05/26/2023]
Abstract
Novel magnetic ground states have been stabilized in two-dimensional (2D) magnets such as skyrmions, with the potential next-generation information technology. Here, we report the experimental observation of a Néel-type skyrmion lattice at room temperature in a single-phase, layered 2D magnet, specifically a 50% Co-doped Fe5GeTe2 (FCGT) system. The thickness-dependent magnetic domain size follows Kittel's law. The static spin textures and spin dynamics in FCGT nanoflakes were studied by Lorentz electron microscopy, variable-temperature magnetic force microscopy, micromagnetic simulations, and magnetotransport measurements. Current-induced skyrmion lattice motion was observed at room temperature, with a threshold current density, jth = 1 × 106 A/cm2. This discovery of a skyrmion lattice at room temperature in a noncentrosymmetric material opens the way for layered device applications and provides an ideal platform for studies of topological and quantum effects in 2D.
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Affiliation(s)
- Hongrui Zhang
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, USA
| | - David Raftrey
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Physics Department, University of California, Santa Cruz, Santa Cruz, CA, USA
| | - Ying-Ting Chan
- Department of Physics and Astronomy, Rutgers University, Piscataway, NJ, USA
| | - Yu-Tsun Shao
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
| | - Rui Chen
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Xiang Chen
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Department of Physics, University of California, Berkeley, Berkeley, CA, USA
| | - Xiaoxi Huang
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, USA
| | - Jonathan T. Reichanadter
- Department of Electrical Engineering, University of California, Berkeley, Berkeley, CA, USA
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, USA
| | - Kaichen Dong
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Sandhya Susarla
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Lucas Caretta
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, USA
| | - Zhen Chen
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
| | - Jie Yao
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Peter Fischer
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Physics Department, University of California, Santa Cruz, Santa Cruz, CA, USA
| | - Jeffrey B. Neaton
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Department of Physics, University of California, Berkeley, Berkeley, CA, USA
- Kavli Energy Nanosciences Institute at Berkeley, Berkeley, CA, USA
| | - Weida Wu
- Department of Physics and Astronomy, Rutgers University, Piscataway, NJ, USA
| | - David A. Muller
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, USA
| | - Robert J. Birgeneau
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Department of Physics, University of California, Berkeley, Berkeley, CA, USA
| | - Ramamoorthy Ramesh
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Department of Physics, University of California, Berkeley, Berkeley, CA, USA
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23
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Abstract
Writing, erasing and computing are three fundamental operations required by any working electronic device. Magnetic skyrmions could be essential bits in promising in emerging topological spintronic devices. In particular, skyrmions in chiral magnets have outstanding properties like compact texture, uniform size, and high mobility. However, creating, deleting, and driving isolated skyrmions, as prototypes of aforementioned basic operations, have been a grand challenge in chiral magnets ever since the discovery of skyrmions, and achieving all these three operations in a single device is even more challenging. Here, by engineering chiral magnet Co8Zn10Mn2 into the customized micro-devices for in-situ Lorentz transmission electron microscopy observations, we implement these three operations of skyrmions using nanosecond current pulses with a low current density of about 1010 A·m−2 at room temperature. A notched structure can create or delete magnetic skyrmions depending on the direction and magnitude of current pulses. We further show that the magnetic skyrmions can be deterministically shifted step-by-step by current pulses, allowing the establishment of the universal current-velocity relationship. These experimental results have immediate significance towards the skyrmion-based memory or logic devices. There has been much interest in using skyrmions for new approaches to compution, however, creating, deleting and driving skyrmions remains a challenge. Here, Wang et al demonstrate all three operations for skyrmions in tailored Co8Zn10Mn2 nanodevices using tailored current pulses.
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24
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Single skyrmion true random number generator using local dynamics and interaction between skyrmions. Nat Commun 2022; 13:722. [PMID: 35132085 PMCID: PMC8821635 DOI: 10.1038/s41467-022-28334-4] [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: 07/29/2021] [Accepted: 01/19/2022] [Indexed: 11/23/2022] Open
Abstract
Magnetic skyrmions are of great interest to both fundamental research and applications in post-von-Neumann computing devices. The successful implementation of skyrmionic devices requires functionalities of skyrmions with effective controls. Here we show that the local dynamics of skyrmions, in contrast to the global dynamics of a skyrmion as a whole, can be introduced to provide effective functionalities for versatile computing. A single skyrmion interacting with local pinning centres under thermal effects can fluctuate in time and switch between a small-skyrmion and a large-skyrmion state, thereby serving as a robust true random number generator for probabilistic computing. Moreover, neighbouring skyrmions exhibit an anti-correlated coupling in their fluctuation dynamics. Both the switching probability and the dynamic coupling strength can be tuned by modifying the applied magnetic field and spin current. Our results could lead to progress in developing magnetic skyrmionic devices with high tunability and efficient controls. Skyrmions, a kind of topological spin texture, have been considered as having potential for use in spin-based computing. Here, Wang et al. study the local dynamics of skyrmions interacting with pinning sites, demonstrating a skyrmion true random number generator with the magnetic field and spin current as two control parameters.
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25
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Makarov D, Volkov OM, Kákay A, Pylypovskyi OV, Budinská B, Dobrovolskiy OV. New Dimension in Magnetism and Superconductivity: 3D and Curvilinear Nanoarchitectures. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2101758. [PMID: 34705309 DOI: 10.1002/adma.202101758] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 05/16/2021] [Indexed: 06/13/2023]
Abstract
Traditionally, the primary field, where curvature has been at the heart of research, is the theory of general relativity. In recent studies, however, the impact of curvilinear geometry enters various disciplines, ranging from solid-state physics over soft-matter physics, chemistry, and biology to mathematics, giving rise to a plethora of emerging domains such as curvilinear nematics, curvilinear studies of cell biology, curvilinear semiconductors, superfluidity, optics, 2D van der Waals materials, plasmonics, magnetism, and superconductivity. Here, the state of the art is summarized and prospects for future research in curvilinear solid-state systems exhibiting such fundamental cooperative phenomena as ferromagnetism, antiferromagnetism, and superconductivity are outlined. Highlighting the recent developments and current challenges in theory, fabrication, and characterization of curvilinear micro- and nanostructures, special attention is paid to perspective research directions entailing new physics and to their strong application potential. Overall, the perspective is aimed at crossing the boundaries between the magnetism and superconductivity communities and drawing attention to the conceptual aspects of how extension of structures into the third dimension and curvilinear geometry can modify existing and aid launching novel functionalities. In addition, the perspective should stimulate the development and dissemination of research and development oriented techniques to facilitate rapid transitions from laboratory demonstrations to industry-ready prototypes and eventual products.
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Affiliation(s)
- Denys Makarov
- Helmholtz-Zentrum Dresden - Rossendorf e.V., Institute of Ion Beam Physics and Materials Research, 01328, Dresden, Germany
| | - Oleksii M Volkov
- Helmholtz-Zentrum Dresden - Rossendorf e.V., Institute of Ion Beam Physics and Materials Research, 01328, Dresden, Germany
| | - Attila Kákay
- Helmholtz-Zentrum Dresden - Rossendorf e.V., Institute of Ion Beam Physics and Materials Research, 01328, Dresden, Germany
| | - Oleksandr V Pylypovskyi
- Helmholtz-Zentrum Dresden - Rossendorf e.V., Institute of Ion Beam Physics and Materials Research, 01328, Dresden, Germany
- Kyiv Academic University, Kyiv, 03142, Ukraine
| | - Barbora Budinská
- Superconductivity and Spintronics Laboratory, Nanomagnetism and Magnonics, Faculty of Physics, University of Vienna, Vienna, 1090, Austria
| | - Oleksandr V Dobrovolskiy
- Superconductivity and Spintronics Laboratory, Nanomagnetism and Magnonics, Faculty of Physics, University of Vienna, Vienna, 1090, Austria
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26
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Experimental demonstration of skyrmionic magnetic tunnel junction at room temperature. Sci Bull (Beijing) 2022; 67:691-699. [DOI: 10.1016/j.scib.2022.01.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 01/07/2022] [Accepted: 01/12/2022] [Indexed: 11/24/2022]
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27
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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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28
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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: 1] [Impact Index Per Article: 0.3] [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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29
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Moon KW, Yang S, Hwang C. Reversible magnetic spiral domain. Sci Rep 2021; 11:20970. [PMID: 34697314 PMCID: PMC8546083 DOI: 10.1038/s41598-021-00016-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 09/28/2021] [Indexed: 12/01/2022] Open
Abstract
The various spiral structures that exist in nature inspire humanity because of their morphological beauty, and spiral structures are used in various fields, including architecture, engineering, and art. Spiral structures have their own winding directions, and in most spirals, it is difficult to reverse the predetermined winding direction. Here, we show that a rotating spiral exists in magnetic systems for which the winding direction can be easily reversed. A magnetization vector basically has a spiral motion combining a precessional and a damping motion. The application of these basic mechanics to a system composed of magnetic vectors that are affected by a radial current and the Dzyaloshinskii–Moriya interaction forms the rotating magnetic spiral. The winding direction of the magnetic spiral has its own stability, but the direction can be changed using an external magnetic field. This magnetic spiral has a finite size, and the magnetic domain is destroyed at the edge of the spiral, which can create magnetic skyrmions.
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Affiliation(s)
- Kyoung-Woong Moon
- Quantum Spin Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
| | - Seungmo Yang
- 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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30
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Quessab Y, Xu J, Morshed MG, Ghosh AW, Kent AD. Interplay between Spin-Orbit Torques and Dzyaloshinskii-Moriya Interactions in Ferrimagnetic Amorphous Alloys. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:e2100481. [PMID: 34338450 PMCID: PMC8456276 DOI: 10.1002/advs.202100481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 06/29/2021] [Indexed: 06/13/2023]
Abstract
Ferrimagnetic thin films are attractive for low-power spintronic applications because of their low magnetization, small angular momentum, and fast spin dynamics. Spin orbit torques (SOT) can be applied with proximal heavy metals that also generate interfacial Dzyaloshinskii-Moriya interactions (DMI), which can stabilize ultrasmall skyrmions and enable fast domain wall motion. Here, the properties of a ferrimagnetic CoGd alloy between two heavy metals to increase the SOT efficiency, while maintaining a significant DMI is studied. SOT switching for various capping layers and alloy compositions shows that Pt/CoGd/(W or Ta) films enable more energy-efficient SOT magnetization switching than Pt/CoGd/Ir. Spin-torque ferromagnetic resonance confirms that Pt/CoGd/W has the highest spin-Hall angle of 16.5%, hence SOT efficiency, larger than Pt/CoGd/(Ta or Ir). Density functional theory calculations indicate that CoGd films capped by W or Ta have the largest DMI energy, 0.38 and 0.32 mJ m-2 , respectively. These results show that Pt/CoGd/W is a very promising ferrimagnetic structure to achieve small skyrmions and to move them efficiently with current.
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Affiliation(s)
- Yassine Quessab
- Center for Quantum Phenomena, Department of PhysicsNew York UniversityNew YorkNY10003USA
| | - Jun‐Wen Xu
- Center for Quantum Phenomena, Department of PhysicsNew York UniversityNew YorkNY10003USA
| | - Md Golam Morshed
- Department of Electrical and Computer EngineeringUniversity of VirginiaCharlottesvilleVA22904USA
| | - Avik W. Ghosh
- Department of Electrical and Computer EngineeringUniversity of VirginiaCharlottesvilleVA22904USA
- Department of PhysicsUniversity of VirginiaCharlottesvilleVirginia22904USA
| | - Andrew D. Kent
- Center for Quantum Phenomena, Department of PhysicsNew York UniversityNew YorkNY10003USA
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31
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Wei W, Tang J, Wu Y, Wang Y, Jiang J, Li J, Soh Y, Xiong Y, Tian M, Du H. Current-Controlled Topological Magnetic Transformations in a Nanostructured Kagome Magnet. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2101610. [PMID: 34224181 DOI: 10.1002/adma.202101610] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 05/14/2021] [Indexed: 06/13/2023]
Abstract
Topological magnetic charge Q is a fundamental parameter that describes the magnetic domains and determines their intriguing electromagnetic properties. The ability to switch Q in a controlled way by electrical methods allows for flexible manipulation of electromagnetic behavior in future spintronic devices. Here, the room-temperature current-controlled topological magnetic transformations between Q = -1 skyrmions and Q = 0 stripes or type-II bubbles in a kagome crystal Fe3 Sn2 are reported. It is shown that reproducible and reversible skyrmion-bubble and skyrmion-stripe transformations can be achieved by tuning the density of nanosecond pulsed current of the order of ≈1010 A m-2 . Further numerical simulations suggest that spin-transfer torque combined with Joule thermal heating effects determine the current-induced topological magnetic transformations.
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Affiliation(s)
- Wensen Wei
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei, 230031, China
| | - Jin Tang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei, 230031, China
| | - Yaodong Wu
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei, 230031, China
- Key Laboratory for Photoelectric Detection Science and Technology of Education Department of Anhui Province, and School of Physics and Materials Engineering, Hefei Normal University, Hefei, 230601, China
| | - Yihao Wang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei, 230031, China
| | - Jialiang Jiang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei, 230031, China
| | - Junbo Li
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei, 230031, China
| | - Yona Soh
- Paul Scherrer Institute, Villigen, 5232, Switzerland
| | - Yimin Xiong
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei, 230031, China
| | - Mingliang Tian
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei, 230031, China
- School of Physics and Materials Science, Anhui University, Hefei, 230601, China
| | - Haifeng Du
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei, 230031, China
- Institutes of Physical Science and Information Technology, Anhui University, Hefei, 230601, China
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32
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Tan AKC, Ho P, Lourembam J, Huang L, Tan HK, Reichhardt CJO, Reichhardt C, Soumyanarayanan A. Visualizing the strongly reshaped skyrmion Hall effect in multilayer wire devices. Nat Commun 2021; 12:4252. [PMID: 34253721 PMCID: PMC8275747 DOI: 10.1038/s41467-021-24114-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 05/28/2021] [Indexed: 12/02/2022] Open
Abstract
Magnetic skyrmions are nanoscale spin textures touted as next-generation computing elements. When subjected to lateral currents, skyrmions move at considerable speeds. Their topological charge results in an additional transverse deflection known as the skyrmion Hall effect (SkHE). While promising, their dynamic phenomenology with current, skyrmion size, geometric effects and disorder remain to be established. Here we report on the ensemble dynamics of individual skyrmions forming dense arrays in Pt/Co/MgO wires by examining over 20,000 instances of motion across currents and fields. The skyrmion speed reaches 24 m/s in the plastic flow regime and is surprisingly robust to positional and size variations. Meanwhile, the SkHE saturates at ∼22∘, is substantially reshaped by the wire edge, and crucially increases weakly with skyrmion size. Particle model simulations suggest that the SkHE size dependence — contrary to analytical predictions — arises from the interplay of intrinsic and pinning-driven effects. These results establish a robust framework to harness SkHE and achieve high-throughput skyrmion motion in wire devices. Skyrmions - nanoscale, topological spin textures - are promising elements for next-generation computing due to their efficient coupling to currents in racetrack devices. Here, Tan et al. examine over 20,000 instances of current induced skyrmion motion to unveil a comprehensive picture of skyrmion dynamics across currents and fields.
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Affiliation(s)
- Anthony K C Tan
- Data Storage Institute, Agency for Science, Technology & Research (A*STAR), Singapore, Singapore.,Cavendish Laboratory, University of Cambridge, Cambridge, UK
| | - Pin Ho
- Data Storage Institute, Agency for Science, Technology & Research (A*STAR), Singapore, Singapore. .,Institute of Materials Research & Engineering, Agency for Science, Technology & Research (A*STAR), Singapore, Singapore.
| | - James Lourembam
- Data Storage Institute, Agency for Science, Technology & Research (A*STAR), Singapore, Singapore.,Institute of Materials Research & Engineering, Agency for Science, Technology & Research (A*STAR), Singapore, Singapore
| | - Lisen Huang
- Data Storage Institute, Agency for Science, Technology & Research (A*STAR), Singapore, Singapore.,Institute of Materials Research & Engineering, Agency for Science, Technology & Research (A*STAR), Singapore, Singapore
| | - Hang Khume Tan
- Data Storage Institute, Agency for Science, Technology & Research (A*STAR), Singapore, Singapore.,Institute of Materials Research & Engineering, Agency for Science, Technology & Research (A*STAR), Singapore, Singapore
| | - Cynthia J O Reichhardt
- Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM, USA
| | - Charles Reichhardt
- Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM, USA
| | - Anjan Soumyanarayanan
- Data Storage Institute, Agency for Science, Technology & Research (A*STAR), Singapore, Singapore. .,Institute of Materials Research & Engineering, Agency for Science, Technology & Research (A*STAR), Singapore, Singapore. .,Physics Department, National University of Singapore, Singapore, Singapore.
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33
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Vizarim NP, Bellizotti Souza JC, Reichhardt C, Reichhardt CJO, Venegas PA. Directional locking and the influence of obstacle density on skyrmion dynamics in triangular and honeycomb arrays. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:305801. [PMID: 33979789 DOI: 10.1088/1361-648x/ac0081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 05/12/2021] [Indexed: 06/12/2023]
Abstract
We numerically examine the dynamics of a single skyrmion driven over triangular and honeycomb obstacle arrays at zero temperature. The skyrmion Hall angleθsk, defined as the angle between the applied external drive and the direction of the skyrmion motion, increases in quantized steps or continuously as a function of the applied drive. For the obstacle arrays studied in this work, the skyrmion exhibits two main directional locking angles ofθsk= -30° and -60°. We show that these directions are privileged due to the obstacle landscape symmetry, and coincide with channels along which the skyrmion may move with few or no obstacle collisions. Here we investigate how changes in the obstacle density can modify the skyrmion Hall angles and cause some dynamic phases to appear or grow while other phases vanish. This interesting behavior can be used to guide skyrmions along designated trajectories via regions with different obstacle densities. For fixed obstacle densities, we investigate the evolution of the lockedθsk= -30° and -60° phases as a function of the Magnus force, and discuss possibilities for switching between these phases using topological selection.
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Affiliation(s)
- N P Vizarim
- POSMAT-Programa de Pós-Graduação em Ciência e Tecnologia de Materiais, Faculdade de Ciências, Universidade Estadual Paulista-UNESP, Bauru, SP, CP 473, 17033-360, Brazil
| | - J C Bellizotti Souza
- Departamento de Física, Faculdade de Ciências, Universidade Estadual Paulista-UNESP, Bauru, SP, CP 473, 17033-360, Brazil
| | - C Reichhardt
- Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States of America
| | - C J O Reichhardt
- Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States of America
| | - P A Venegas
- Departamento de Física, Faculdade de Ciências, Universidade Estadual Paulista-UNESP, Bauru, SP, CP 473, 17033-360, Brazil
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34
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Jena SK, Islam R, Milińska E, Jakubowski MM, Minikayev R, Lewińska S, Lynnyk A, Pietruczik A, Aleszkiewicz P, Autieri C, Wawro A. Interfacial Dzyaloshinskii-Moriya interaction in the epitaxial W/Co/Pt multilayers. NANOSCALE 2021; 13:7685-7693. [PMID: 33928952 DOI: 10.1039/d0nr08594d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The Dzyaloshinskii-Moriya interaction (DMI) manifesting in asymmetric layered ferromagnetic films gives rise to non-colinear spin structures stabilizing magnetization configurations with nontrivial topology. In this work magnetization reversal, magnetic domain alignment, and strength of DMI are related to the crystalline structure of W/Co/Pt multilayers grown by molecular beam epitaxy. The applied growth method enables the fabrication of layered systems with higher crystalline quality than commonly applied sputtering techniques. A relatively high value of the D coefficient was determined from the aligned magnetic domain stripe structure, substantially exceeding 2 mJ m-2. The highest value of DMI strength Deff = 2.64 mJ m-2 and surface DMI parameter DS = 1.83 pJ m-1 have been observed for a repetition number equal to 10. The experimental results correlate exactly with those obtained from the micromagnetic modelling and density functional theory calculations performed for the well-defined layered stacks. This high value of DMI strength originates from the additive contributions of the interfacial atomic Co layers at the two types of interfaces.
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Affiliation(s)
- Sukanta Kumar Jena
- Institute of Physics Polish Academy of Sciences, aleja Lotników 32/46, PL-02668 Warsaw, Poland.
| | - Rajibul Islam
- International Research Centre for Interfacing Magnetism and Superconductivity with Topological Matter, Institute of Physics Polish Academy of Sciences, aleja Lotników 32/46, PL-02668 Warsaw, Poland
| | - Ewelina Milińska
- Institute of Physics Polish Academy of Sciences, aleja Lotników 32/46, PL-02668 Warsaw, Poland.
| | - Marcin M Jakubowski
- Institute of Physics Polish Academy of Sciences, aleja Lotników 32/46, PL-02668 Warsaw, Poland.
| | - Roman Minikayev
- Institute of Physics Polish Academy of Sciences, aleja Lotników 32/46, PL-02668 Warsaw, Poland.
| | - Sabina Lewińska
- Institute of Physics Polish Academy of Sciences, aleja Lotników 32/46, PL-02668 Warsaw, Poland.
| | - Artem Lynnyk
- Institute of Physics Polish Academy of Sciences, aleja Lotników 32/46, PL-02668 Warsaw, Poland.
| | - Aleksiej Pietruczik
- Institute of Physics Polish Academy of Sciences, aleja Lotników 32/46, PL-02668 Warsaw, Poland.
| | - Paweł Aleszkiewicz
- Institute of Physics Polish Academy of Sciences, aleja Lotników 32/46, PL-02668 Warsaw, Poland.
| | - Carmine Autieri
- International Research Centre for Interfacing Magnetism and Superconductivity with Topological Matter, Institute of Physics Polish Academy of Sciences, aleja Lotników 32/46, PL-02668 Warsaw, Poland and Consiglio Nazionale delle Ricerche CNR-SPIN, UOS Salerno, I-84084 Fisciano, Salerno, Italy
| | - Andrzej Wawro
- Institute of Physics Polish Academy of Sciences, aleja Lotników 32/46, PL-02668 Warsaw, Poland.
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35
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Discrimination of skyrmion chirality via spin-orbit and -transfer torques for logic operation. Sci Rep 2021; 11:8415. [PMID: 33863985 PMCID: PMC8052369 DOI: 10.1038/s41598-021-87742-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 03/31/2021] [Indexed: 11/08/2022] Open
Abstract
Recently many works on magnetic memories and logic circuits, which use a magnetic skyrmion have been reported. Previously we micromagnetically simulated a method to switch a chirality of a magnetic skyrmion formed in a magnetic thin film by introducing a pulsed heat spot. In this paper, we propose a method to discriminate the chirality of a skyrmion in a branched nanowire by using spin–orbit torque (SOT) and spin-transfer torque (STT), and confirm the validity of the method by using simulation. The simulated results show that the motion changes depending on the chirality when additional SOT is applied on a skyrmion moving in a branch by STT. This method can be used as a fundamental building block for electrical detection in memory and logic devices using the chirality of skyrmions as a data bit in addition to the presence (and polarity) of the skyrmions as conventionally used, which can be lead to multiple-valued operation.
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36
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Juge R, Bairagi K, Rana KG, Vogel J, Sall M, Mailly D, Pham VT, Zhang Q, Sisodia N, Foerster M, Aballe L, Belmeguenai M, Roussigné Y, Auffret S, Buda-Prejbeanu LD, Gaudin G, Ravelosona D, Boulle O. Helium Ions Put Magnetic Skyrmions on the Track. NANO LETTERS 2021; 21:2989-2996. [PMID: 33740371 DOI: 10.1021/acs.nanolett.1c00136] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Magnetic skyrmions are deemed to be the forerunners of novel spintronic memory and logic devices. While their observation and their current-driven motion at room temperature have been demonstrated, certain issues regarding their nucleation, stability, pinning, and skyrmion Hall effect still need to be overcome to realize functional devices. Here, we demonstrate that focused He+-ion-irradiation can be used to create and guide skyrmions in racetracks. We show that the reduction of the perpendicular magnetic anisotropy and Dzyaloshinskii-Moriya interaction in the track defined by ion-irradiation leads to the formation of stable isolated skyrmions. Current-driven skyrmion motion experiments and simulations reveal that the skyrmions move along the irradiated track, resulting in the suppression of the skyrmion Hall effect, and that the maximum skyrmion velocity can be enhanced by tuning the magnetic properties. These results open up a new path to nucleate and guide magnetic skyrmions in racetrack devices.
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Affiliation(s)
- Roméo Juge
- Univ. Grenoble Alpes, CNRS, CEA, Grenoble INP, Spintec, 38000 Grenoble, France
| | - Kaushik Bairagi
- Univ. Grenoble Alpes, CNRS, CEA, Grenoble INP, Spintec, 38000 Grenoble, France
| | - Kumari Gaurav Rana
- Univ. Grenoble Alpes, CNRS, CEA, Grenoble INP, Spintec, 38000 Grenoble, France
| | - Jan Vogel
- Univ. Grenoble Alpes, CNRS, Institut Néel, Grenoble, France
| | - Mamour Sall
- Spin-Ion Technologies, 91120 Palaiseau, France
| | - Dominique Mailly
- Centre de Nanosciences et de Nanotechnologies, CNRS, Université Paris-Saclay, 91120 Palaiseau, France
| | - Van Tuong Pham
- Univ. Grenoble Alpes, CNRS, CEA, Grenoble INP, Spintec, 38000 Grenoble, France
| | - Qiang Zhang
- Univ. Grenoble Alpes, CNRS, CEA, Grenoble INP, Spintec, 38000 Grenoble, France
| | - Naveen Sisodia
- Univ. Grenoble Alpes, CNRS, CEA, Grenoble INP, Spintec, 38000 Grenoble, France
| | - Michael Foerster
- ALBA Synchrotron Light Facility, 08290 Cerdanyola del Vallès, Barcelona, Spain
| | - Lucia Aballe
- ALBA Synchrotron Light Facility, 08290 Cerdanyola del Vallès, Barcelona, Spain
| | - Mohamed Belmeguenai
- Laboratoire des Sciences des Procédés et des Matériaux, CNRS, Université Sorbonne Paris Nord, 93430 Villetaneuse, France
| | - Yves Roussigné
- Laboratoire des Sciences des Procédés et des Matériaux, CNRS, Université Sorbonne Paris Nord, 93430 Villetaneuse, France
| | - Stéphane Auffret
- Univ. Grenoble Alpes, CNRS, CEA, Grenoble INP, Spintec, 38000 Grenoble, France
| | | | - Gilles Gaudin
- Univ. Grenoble Alpes, CNRS, CEA, Grenoble INP, Spintec, 38000 Grenoble, France
| | - Dafiné Ravelosona
- Spin-Ion Technologies, 91120 Palaiseau, France
- Centre de Nanosciences et de Nanotechnologies, CNRS, Université Paris-Saclay, 91120 Palaiseau, France
| | - Olivier Boulle
- Univ. Grenoble Alpes, CNRS, CEA, Grenoble INP, Spintec, 38000 Grenoble, France
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37
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Abstract
Skyrmion, a concept originally proposed in particle physics half a century ago, can now find the most fertile field for its applicability, that is, the magnetic skyrmion realized in helimagnetic materials. The spin swirling vortex-like texture of the magnetic skyrmion can define the particle nature by topology; that is, all the constituent spin moments within the two-dimensional sheet wrap the sphere just one time. Such a topological nature of the magnetic skyrmion can lead to extraordinary metastability via topological protection and the driven motion with low electric-current excitation, which may promise future application to spintronics. The skyrmions in the magnetic materials frequently show up as the crystal lattice form, e.g., hexagonal lattice, but sometimes as isolated or independent particles. These skyrmions in magnets were initially found in acentric magnets, such as chiral, polar, and bilayered magnets endowed with antisymmetric spin exchange interaction, while the skyrmion host materials have been explored in a broader family of compounds including centrosymmetric magnets. This review describes the materials science and materials chemistry of magnetic skyrmions using the classification scheme of the skyrmion forming microscopic mechanisms. The emergent phenomena and functions mediated by skyrmions are described, including the generation of emergent magnetic and electric field by statics and dynamics of skrymions and the inherent magnetoelectric effect. The other important magnetic topological defects in two or three dimensions, such as biskyrmions, antiskyrmions, merons, and hedgehogs, are also reviewed in light of their interplay with the skyrmions.
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Affiliation(s)
- Yoshinori Tokura
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan.,RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan.,Tokyo College, University of Tokyo, Tokyo 113-8656, Japan
| | - Naoya Kanazawa
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
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38
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Fernández Scarioni A, Barton C, Corte-León H, Sievers S, Hu X, Ajejas F, Legrand W, Reyren N, Cros V, Kazakova O, Schumacher HW. Thermoelectric Signature of Individual Skyrmions. PHYSICAL REVIEW LETTERS 2021; 126:077202. [PMID: 33666484 DOI: 10.1103/physrevlett.126.077202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 06/26/2020] [Accepted: 11/02/2020] [Indexed: 06/12/2023]
Abstract
We experimentally study the thermoelectrical signature of individual skyrmions in chiral Pt/Co/Ru multilayers. Using a combination of controlled nucleation, single skyrmion annihilation, and magnetic field dependent measurements the thermoelectric signature of individual skyrmions is characterized. The observed signature is explained by the anomalous Nernst effect of the skyrmion's spin structure. Possible topological contributions to the observed thermoelectrical signature are discussed. Such thermoelectrical characterization allows for noninvasive detection and counting of skyrmions and enables fundamental studies of topological thermoelectric effects on the nanoscale.
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Affiliation(s)
| | - Craig Barton
- National Physical Laboratory, Teddington TW110LW, United Kingdom
| | | | - Sibylle Sievers
- Physikalisch-Technische Bundesanstalt, 38116 Braunschweig, Germany
| | - Xiukun Hu
- Physikalisch-Technische Bundesanstalt, 38116 Braunschweig, Germany
| | - Fernando Ajejas
- Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, 91767 Palaiseau, France
| | - William Legrand
- Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, 91767 Palaiseau, France
| | - Nicolas Reyren
- Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, 91767 Palaiseau, France
| | - Vincent Cros
- Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, 91767 Palaiseau, France
| | - Olga Kazakova
- National Physical Laboratory, Teddington TW110LW, United Kingdom
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39
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Je SG, Thian D, Chen X, Huang L, Jung DH, Chao W, Lee KS, Hong JI, Soumyanarayanan A, Im MY. Targeted Writing and Deleting of Magnetic Skyrmions in Two-Terminal Nanowire Devices. NANO LETTERS 2021; 21:1253-1259. [PMID: 33481614 DOI: 10.1021/acs.nanolett.0c03686] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Controllable writing and deleting of nanoscale magnetic skyrmions are key requirements for their use as information carriers for next-generation memory and computing technologies. While several schemes have been proposed, they require complex fabrication techniques or precisely tailored electrical inputs, which limits their long-term scalability. Here, we demonstrate an alternative approach for writing and deleting skyrmions using conventional electrical pulses within a simple, two-terminal wire geometry. X-ray microscopy experiments and micromagnetic simulations establish the observed skyrmion creation and annihilation as arising from Joule heating and Oersted field effects of the current pulses, respectively. The unique characteristics of these writing and deleting schemes, such as spatial and temporal selectivity, together with the simplicity of the two-terminal device architecture, provide a flexible and scalable route to the viable applications of skyrmions.
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Affiliation(s)
- Soong-Geun Je
- Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Department of Emerging Materials Science, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
- Department of Physics, Chonnam National University, Gwangju 61186, Korea
| | - Dickson Thian
- Institute of Materials Research and Engineering, Agency for Science, Technology, and Research, 138634 Singapore
| | - Xiaoye Chen
- Institute of Materials Research and Engineering, Agency for Science, Technology, and Research, 138634 Singapore
- Data Storage Institute, Agency for Science, Technology, and Research, 138634 Singapore
| | - Lisen Huang
- Institute of Materials Research and Engineering, Agency for Science, Technology, and Research, 138634 Singapore
- Data Storage Institute, Agency for Science, Technology, and Research, 138634 Singapore
| | - Dae-Han Jung
- School of Materials Science and Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Korea
| | - Weilun Chao
- Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Ki-Suk Lee
- School of Materials Science and Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Korea
| | - Jung-Il Hong
- Department of Emerging Materials Science, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
| | - Anjan Soumyanarayanan
- Institute of Materials Research and Engineering, Agency for Science, Technology, and Research, 138634 Singapore
- Data Storage Institute, Agency for Science, Technology, and Research, 138634 Singapore
- Department of Physics, National University of Singapore, 117551 Singapore
| | - Mi-Young Im
- Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Department of Emerging Materials Science, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
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40
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Ba Y, Zhuang S, Zhang Y, Wang Y, Gao Y, Zhou H, Chen M, Sun W, Liu Q, Chai G, Ma J, Zhang Y, Tian H, Du H, Jiang W, Nan C, Hu JM, Zhao Y. Electric-field control of skyrmions in multiferroic heterostructure via magnetoelectric coupling. Nat Commun 2021; 12:322. [PMID: 33436572 PMCID: PMC7803786 DOI: 10.1038/s41467-020-20528-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 11/30/2020] [Indexed: 11/09/2022] Open
Abstract
Room-temperature skyrmions in magnetic multilayers are considered to be promising candidates for the next-generation spintronic devices. Several approaches have been developed to control skyrmions, but they either cause significant heat dissipation or require ultrahigh electric fields near the breakdown threshold. Here, we demonstrate electric-field control of skyrmions through strain-mediated magnetoelectric coupling in ferromagnetic/ferroelectric multiferroic heterostructures. We show the process of non-volatile creation of multiple skyrmions, reversible deformation and annihilation of a single skyrmion by performing magnetic force microscopy with in situ electric fields. Strain-induced changes in perpendicular magnetic anisotropy and interfacial Dzyaloshinskii–Moriya interaction strength are characterized experimentally. These experimental results, together with micromagnetic simulations, demonstrate that strain-mediated magnetoelectric coupling (via strain-induced changes in both the perpendicular magnetic anisotropy and interfacial Dzyaloshinskii–Moriya interaction is responsible for the observed electric-field control of skyrmions. Our work provides a platform to investigate electric-field control of skyrmions in multiferroic heterostructures and paves the way towards more energy-efficient skyrmion-based spintronics. The common approaches to control of skymions cause significant heat dissipation or require high electric fields near the breakdown threshold. Here, the authors demonstrate electric-field control of skyrmions through strain-mediated magnetoelectric coupling in multiferroic heterostructures.
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Affiliation(s)
- You Ba
- Department of Physics, State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing, 100084, China.,Frontier Science Center for Quantum Information, Tsinghua University, Beijing, 100084, China
| | - Shihao Zhuang
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Yike Zhang
- Department of Physics, State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing, 100084, China.,Frontier Science Center for Quantum Information, Tsinghua University, Beijing, 100084, China
| | - Yutong Wang
- Department of Physics, State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing, 100084, China.,Frontier Science Center for Quantum Information, Tsinghua University, Beijing, 100084, China
| | - Yang Gao
- Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou, 730000, China
| | - Hengan Zhou
- Department of Physics, State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing, 100084, China.,Frontier Science Center for Quantum Information, Tsinghua University, Beijing, 100084, China
| | - Mingfeng Chen
- School of Materials Science and Engineering, State Key Laboratory of New Ceramics and Fine Processing, Tsinghua University, Beijing, 100084, China
| | - Weideng Sun
- Department of Physics, State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing, 100084, China.,Frontier Science Center for Quantum Information, Tsinghua University, Beijing, 100084, China
| | - Quan Liu
- Department of Physics, State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing, 100084, China.,Frontier Science Center for Quantum Information, Tsinghua University, Beijing, 100084, China
| | - Guozhi Chai
- Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou, 730000, China
| | - Jing Ma
- School of Materials Science and Engineering, State Key Laboratory of New Ceramics and Fine Processing, Tsinghua University, Beijing, 100084, China
| | - Ying Zhang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Huanfang Tian
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Haifeng Du
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory of Chinese Academy of Sciences, University of Science and Technology of China, Hefei, 230031, China
| | - Wanjun Jiang
- Department of Physics, State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing, 100084, China.,Frontier Science Center for Quantum Information, Tsinghua University, Beijing, 100084, China
| | - Cewen Nan
- School of Materials Science and Engineering, State Key Laboratory of New Ceramics and Fine Processing, Tsinghua University, Beijing, 100084, China
| | - Jia-Mian Hu
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA.
| | - Yonggang Zhao
- Department of Physics, State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing, 100084, China. .,Frontier Science Center for Quantum Information, Tsinghua University, Beijing, 100084, China.
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41
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Pei K, Liu S, Zhang E, Zhao X, Yang L, Ai L, Li Z, Xiu F, Che R. Anomalous Spin Behavior in Fe 3GeTe 2 Driven by Current Pulses. ACS NANO 2020; 14:9512-9520. [PMID: 32538609 DOI: 10.1021/acsnano.0c03269] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Recently, 2D ferromagnetic materials have aroused wide interest for their magnetic properties and potential applications in spintronic and topological devices. However, their actual applications have been severely hindered by intricate challenges such as the unclear spin arrangement. In particular, the evolution of spin texture driven by high-density electron current, which is an essential condition for fabricating devices, remains unclear. Herein, the current-pulse-driven spin textures in 2D ferromagnetic material Fe3GeTe2 have been thoroughly investigated by in situ Lorentz transmission electron microscopy. The dynamic experiments reveal that the stripe domain structure in the AB and AC planes can be broken and rearranged by the high-density current. In particular, the density of domain walls can be modulated, which offers an avenue to achieve a high-density domain structure. This phenomenon is attributed to the weak interlayer exchange interaction in 2D metallic ferromagnetic materials and the strong disturbance from the high-density current. Therefore, a bubble domain structure and random magnetization in Fe3GeTe2 can be acquired by synchronous current pulses and magnetic fields. These achievements reveal domain structure transitions driven by the current in 2D metallic magnetic materials and provide references for the practical applications.
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Affiliation(s)
- Ke Pei
- Laboratory of Advanced Materials, Department of Materials Science, Collaborative Innovation Center of Chemistry for Energy Materials(iChEM), Fudan University, Shanghai 200433, China
| | - Shanshan Liu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Enze Zhang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Xuebing Zhao
- Laboratory of Advanced Materials, Department of Materials Science, Collaborative Innovation Center of Chemistry for Energy Materials(iChEM), Fudan University, Shanghai 200433, China
| | - Liting Yang
- Laboratory of Advanced Materials, Department of Materials Science, Collaborative Innovation Center of Chemistry for Energy Materials(iChEM), Fudan University, Shanghai 200433, China
| | - Linfeng Ai
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Zihan Li
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Faxian Xiu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - Renchao Che
- Laboratory of Advanced Materials, Department of Materials Science, Collaborative Innovation Center of Chemistry for Energy Materials(iChEM), Fudan University, Shanghai 200433, China
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42
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Fernandes IL, Chico J, Lounis S. Impurity-dependent gyrotropic motion, deflection and pinning of current-driven ultrasmall skyrmions in PdFe/Ir(111) surface. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:425802. [PMID: 32541095 DOI: 10.1088/1361-648x/ab9cf0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 06/15/2020] [Indexed: 06/11/2023]
Abstract
Resting on multi-scale modelling simulations, we explore dynamical aspects characterizing magnetic skyrmions driven by spin-transfer-torque towards repulsive and pinning 3dand 4dsingle atomic defects embedded in a Pd layer deposited on the Fe/Ir(111) surface. The latter is known to host sub-10 nm skyrmions which are of great interest in information technology. The Landau-Lifshitz-Gilbert equation is parametrized with magnetic exchange interactions extracted from the ab-initio all-electron full potential Korringa-Kohn-Rostoker Green function method, where spin-orbit coupling is added self-consistently. Depending on the nature of the defect and the magnitude of the applied magnetic field, the skyrmion deforms by either shrinking or increasing in size, experiencing thereby elliptical distortions. After applying a magnetic field of 10 T, ultrasmall skyrmions are driven along a straight line towards the various defects which permits a simple analysis of the impact of the impurities. Independently from the nature of the skyrmion-defect complex interaction, being repulsive or pinning, a gyrotropic motion is observed. A repulsive force leads to a skyrmion trajectory similar to the one induced by an attractive one. We unveil that the circular motion is clockwise around pinning impurities but counter clockwise around the repulsive ones, which can be used to identify the interaction nature of the defects by observing the skyrmions trajectories. Moreover, and as expected, the skyrmion always escapes the repulsive defects in contrast to the pinning defects, which require a minimal depinning current to observe impurity avoidance. This unveils the richness of the motion regimes of skyrmions. We discuss the results of the simulations in terms of the Thiele equation, which provides a reasonable qualitative description of the observed phenomena. Finally, we show an example of a double track made of pinning impurities, where the engineering of their mutual distance allows to control the skyrmion motion with enhanced velocity.
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Affiliation(s)
- Imara Lima Fernandes
- Peter Grünberg Institut and Institute of Advanced Simulation, Forschungszentrum Jülich & JARA, 52425 Jülich, Germany
| | - Jonathan Chico
- Peter Grünberg Institut and Institute of Advanced Simulation, Forschungszentrum Jülich & JARA, 52425 Jülich, Germany
| | - Samir Lounis
- Peter Grünberg Institut and Institute of Advanced Simulation, Forschungszentrum Jülich & JARA, 52425 Jülich, Germany
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43
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Xu Z, Hwee Wong GD, Tang J, Liu E, Gan W, Xu F, Lew WS. Giant Spin Hall Effect in Cu-Tb Alloy Thin Films. ACS APPLIED MATERIALS & INTERFACES 2020; 12:32898-32904. [PMID: 32608235 DOI: 10.1021/acsami.0c07441] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We report the giant spin current generation in CuTb alloys arising from the spin Hall effect. The maximum spin Hall angle from our CuTb-based magnetic heterostructures was found to be -0.35 ± 0.02 for Cu0.39Tb0.61. We find that the contribution of skew scattering is larger than the side jump for lower Tb concentrations (<14.9%), while the converse is true for higher Tb concentrations. Additionally, we also studied the Gilbert damping parameter, spin diffusion length, and spin-mixing conductance. Interfacial spin transparency was found to be 0.55 ± 0.03 for the CoFeB/Cu0.53Tb0.47 interface. The spin diffusion length and spin-mixing conductance of the Cu0.53Tb0.47 alloy are λsd = 2.5 ± 0.3 nm and G↓↑ = (24.2 ± 1.0) × 1015 cm-2, respectively. Our results pave a way for rare-earth metals to be used as a spin Hall material in highly efficient SOT devices.
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Affiliation(s)
- Zhan Xu
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
- MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Grayson Dao Hwee Wong
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
| | - Jiaxuan Tang
- MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Er Liu
- MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Weiliang Gan
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
| | - Feng Xu
- MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Wen Siang Lew
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
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44
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Capic D, Garanin DA, Chudnovsky EM. Skyrmion-skyrmion interaction in a magnetic film. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:415803. [PMID: 32526724 DOI: 10.1088/1361-648x/ab9bc8] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 06/11/2020] [Indexed: 06/11/2023]
Abstract
Interaction of two skyrmions stabilized by the ferromagnetic exchange, Dzyaloshinskii-Moriya interaction (DMI), and external magnetic field has been studied numerically on a 2D lattice of size large compared to the separation,d, between the skyrmions. We show that two skyrmions of the same chirality (determined by the symmetry of the crystal) repel. In accordance with earlier analytical results, their long-range pair interaction falls out with the separation as exp(-d/δH), whereδHis the magnetic screening length, independent of the DMI. The prefactor in this expression depends on the DMI that drives the repulsion. The latter results in the spiral motion of the two skyrmions around each other, with the separation between them growing logarithmically with time. When two skyrmions of the total topological chargeQ= 2 are pushed close to each other, the discreteness of the atomic lattice makes them collapse into one skyrmion of chargeQ= 1 below a critical separation. Experiment is proposed that would allow one to measure the interaction between two skyrmions by holding them in positions with two magnetic tips. Our findings should be of value for designing topologically protected magnetic memory based upon skyrmions.
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Affiliation(s)
- D Capic
- Physics Department, Herbert H. Lehman College and Graduate School, The City University of New York, 250 Bedford Park Boulevard West, Bronx, New York 10468-1589, United States of America
| | - D A Garanin
- Physics Department, Herbert H. Lehman College and Graduate School, The City University of New York, 250 Bedford Park Boulevard West, Bronx, New York 10468-1589, United States of America
| | - E M Chudnovsky
- Physics Department, Herbert H. Lehman College and Graduate School, The City University of New York, 250 Bedford Park Boulevard West, Bronx, New York 10468-1589, United States of America
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45
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Denisov KS. Theory of an electron asymmetric scattering on skyrmion textures in two-dimensional systems. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:415302. [PMID: 32454477 DOI: 10.1088/1361-648x/ab966e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 05/26/2020] [Indexed: 06/11/2023]
Abstract
We discuss in detail the electron scattering pattern on skyrmion-like magnetic textures in two-dimensional geometry. The special attention is focused on analyzing the scattering asymmetry, which is a precursor of the topological Hall effect. We present analytical results valid in the limiting regimes of strong and weak coupling, we analyze analytically the conditions when the transverse response acquires a quantized character determined by the topological charge of a magnetic texture, we also derive the numerical scheme that gives access to the exact solution of the scattering problem. We describe how the electron scattering asymmetry is modified due to an additional short-range impurity located inside a magnetic skyrmion. Based on the numerical computations we investigate the properties of the asymmetric scattering for an arbitrary magnitude of the interaction strength and the topology of a magnetic texture, we also account for the presence or absence of a scalar impurity.
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Affiliation(s)
- K S Denisov
- Ioffe Institute, 194021 St. Petersburg, Russia
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46
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Yu XZ, Morikawa D, Nakajima K, Shibata K, Kanazawa N, Arima T, Nagaosa N, Tokura Y. Motion tracking of 80-nm-size skyrmions upon directional current injections. SCIENCE ADVANCES 2020; 6:eaaz9744. [PMID: 32596450 PMCID: PMC7299614 DOI: 10.1126/sciadv.aaz9744] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 05/05/2020] [Indexed: 05/29/2023]
Abstract
Nanometer-scale skyrmions are prospective candidates for information bits in low-power consumption devices owing to their topological nature and controllability with low current density. Studies on skyrmion dynamics in different classes of materials have exploited the topological Hall effect and current-driven fast motion of skyrmionic bubbles. However, the small current track motion of a single skyrmion and few-skyrmion aggregates remains elusive. Here, we report the tracking of creation and extinction and motion of 80-nm-size skyrmions upon directional one-current pulse excitations at low current density of the order of 109 A m-2 in designed devices with the notched hole. The Hall motion of a single skyrmion and the torque motions of few-skyrmion aggregates have been directly revealed. The results exemplify low-current density controls of skyrmions, which will pave the way for the application of skyrmions.
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Affiliation(s)
- X. Z. Yu
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
| | - D. Morikawa
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
| | - K. Nakajima
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
| | - K. Shibata
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
| | - N. Kanazawa
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
| | - T. Arima
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
- Department of Advanced Materials Science, University of Tokyo, Kashiwa 277-8561, Japan
| | - N. Nagaosa
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
| | - Y. Tokura
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
- Tokyo College, University of Tokyo, Tokyo 113-8656, Japan
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47
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Reichhardt C, Reichhardt CJO. Dynamics of Magnus-dominated particle clusters, collisions, pinning, and ratchets. Phys Rev E 2020; 101:062602. [PMID: 32688521 DOI: 10.1103/physreve.101.062602] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 05/19/2020] [Indexed: 12/26/2022]
Abstract
Motivated by the recent work in skyrmions and active chiral matter systems, we examine pairs and small clusters of repulsively interacting point particles in the limit where the dynamics is dominated by the Magnus force. We find that particles with the same Magnus force can form stable pairs, triples, and higher ordered clusters or exhibit chaotic motion. For mixtures of particles with opposite Magnus force, particle pairs can combine to form translating dipoles. Under an applied drive, particles with the same Magnus force translate; however, particles with different or opposite Magnus force exhibit a drive-dependent decoupling transition. When the particles interact with a repulsive obstacle, they can form localized orbits with depinning or unwinding transitions under an applied drive. We examine the interaction of these particles with clusters or lines of obstacles and find that the particles can become trapped in orbits that encircle multiple obstacles. Under an ac drive, we observe a series of ratchet effects, including ratchet reversals, for particles interacting with a line of obstacles due to the formation of commensurate orbits. Finally, in assemblies of particles with mixed Magnus forces of the same sign, we find that the particles with the largest Magnus force become localized in the center of the cluster, while for mixtures with opposite Magnus forces, the motion is dominated by transient local pairs or clusters, where the translating pairs can be regarded as a form of active matter.
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Affiliation(s)
- C Reichhardt
- Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - C J O Reichhardt
- Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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48
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Quessab Y, Xu JW, Ma CT, Zhou W, Riley GA, Shaw JM, Nembach HT, Poon SJ, Kent AD. Tuning interfacial Dzyaloshinskii-Moriya interactions in thin amorphous ferrimagnetic alloys. Sci Rep 2020; 10:7447. [PMID: 32366864 PMCID: PMC7198596 DOI: 10.1038/s41598-020-64427-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 04/15/2020] [Indexed: 11/26/2022] Open
Abstract
Skyrmions can be stabilized in magnetic systems with broken inversion symmetry and chiral interactions, such as Dzyaloshinskii-Moriya interactions (DMI). Further, compensation of magnetic moments in ferrimagnetic materials can significantly reduce magnetic dipolar interactions, which tend to favor large skyrmions. Tuning DMI is essential to control skyrmion properties, with symmetry breaking at interfaces offering the greatest flexibility. However, in contrast to the ferromagnet case, few studies have investigated interfacial DMI in ferrimagnets. Here we present a systematic study of DMI in ferrimagnetic CoGd films by Brillouin light scattering. We demonstrate the ability to control DMI by the CoGd cap layer composition, the stack symmetry and the ferrimagnetic layer thickness. The DMI thickness dependence confirms its interfacial nature. In addition, magnetic force microscopy reveals the ability to tune DMI in a range that stabilizes sub-100 nm skyrmions at room temperature in zero field. Our work opens new paths for controlling interfacial DMI in ferrimagnets to nucleate and manipulate skyrmions.
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Affiliation(s)
- Y Quessab
- Center for Quantum Phenomena, Department of Physics, New York University, New York, New York, 10003, USA.
| | - J-W Xu
- Center for Quantum Phenomena, Department of Physics, New York University, New York, New York, 10003, USA
| | - C T Ma
- Department of Physics, University of Virginia, Charlottesville, Virginia, 22904, USA
| | - W Zhou
- Department of Physics, University of Virginia, Charlottesville, Virginia, 22904, USA
| | - G A Riley
- Quantum Electromagnetics Division, National Institute of Standards and Technology, Boulder, Colorado, 80305, USA
- Center for Memory and Recording Research, University of California San Diego, La Jolla, California, 92093, USA
| | - J M Shaw
- Quantum Electromagnetics Division, National Institute of Standards and Technology, Boulder, Colorado, 80305, USA
| | - H T Nembach
- Quantum Electromagnetics Division, National Institute of Standards and Technology, Boulder, Colorado, 80305, USA
- JILA, University of Colorado, Boulder, Colorado, 80309, USA
| | - S J Poon
- Department of Physics, University of Virginia, Charlottesville, Virginia, 22904, USA
| | - A D Kent
- Center for Quantum Phenomena, Department of Physics, New York University, New York, New York, 10003, USA
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49
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Sáenz-Trevizo A, Hodge AM. Nanomaterials by design: a review of nanoscale metallic multilayers. NANOTECHNOLOGY 2020; 31:292002. [PMID: 32186280 DOI: 10.1088/1361-6528/ab803f] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Nanoscale metallic multilayers have been shown to have a wide range of outstanding properties, which differ to a great extent from those observed in monolithic films. Their exceptional properties are mainly associated with the large number of interfaces and the nanoscale layer thicknesses. Many studies have investigated these materials focusing on magnetic, mechanical, optical, or radiation tolerance properties. Thus, this review provides a summary of the findings in each area, including a description of the general attributes, the adopted synthesis methods and most common characterization techniques used. This information is followed by a compendium of the material properties and a brief discussion of related experimental data, as well as existing and promising applications. Other phenomena of interest, including thermal stability studies, self-propagating reactions and the progression from nano multilayers to amorphous and/or crystalline alloys, are also covered. In general, this review highlights the use of nano multilayer architectures as viable routes to overcome the challenges of designing and implementing new engineering materials at the nanoscale.
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Affiliation(s)
- A Sáenz-Trevizo
- Department of Aerospace and Mechanical Engineering, University of Southern California, 854 Downey Way, Los Angeles, CA 90089, United States of America
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50
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Zhang X, Zhou Y, Mee Song K, Park TE, Xia J, Ezawa M, Liu X, Zhao W, Zhao G, Woo S. Skyrmion-electronics: writing, deleting, reading and processing magnetic skyrmions toward spintronic applications. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:143001. [PMID: 31689688 DOI: 10.1088/1361-648x/ab5488] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The field of magnetic skyrmions has been actively investigated across a wide range of topics during the last decades. In this topical review, we mainly review and discuss key results and findings in skyrmion research since the first experimental observation of magnetic skyrmions in 2009. We particularly focus on the theoretical, computational and experimental findings and advances that are directly relevant to the spintronic applications based on magnetic skyrmions, i.e. their writing, deleting, reading and processing driven by magnetic field, electric current and thermal energy. We then review several potential applications including information storage, logic computing gates and non-conventional devices such as neuromorphic computing devices. Finally, we discuss possible future research directions on magnetic skyrmions, which also cover rich topics on other topological textures such as antiskyrmions and bimerons in antiferromagnets and frustrated magnets.
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Affiliation(s)
- Xichao Zhang
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, People's Republic of China
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