1
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Sun C, Zhang X, Xie Y, Zhou Y, Gao X. True and False Chirality in Chiral Magnetic Nanoparticles. J Phys Chem Lett 2024:4679-4685. [PMID: 38656159 DOI: 10.1021/acs.jpclett.4c01016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Determining the true or false chirality of a system is essential for the design of advanced chiral materials and for improving their applications. Typically, a magnetic field would cause false optical activity in the chiral material system, thus confusing the true chirality's influence. Here, we provide a simple way to uncover the true and false chirality in chiral ferrimagnetic nanoparticles (FNPs) by using the gel as a rigid frame. The remnant local magnetic field of the FNP gel can be easily adjusted by an external magnetic field or by controlling the concentration of the FNPs. Moreover, the potential application of the FNP gel is detected by induced magnetic circularly polarized luminescence. This work provides deep insight into the true and false chirality in magnetic nanosystems and offers a strategy to construct new optic elements with an adjustable local magnetic field.
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Affiliation(s)
- Chao Sun
- Wenzhou Key Laboratory of Biophysics, Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, Zhejiang 325000, P. R. China
| | - Xueyan Zhang
- Wenzhou Key Laboratory of Biophysics, Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, Zhejiang 325000, P. R. China
| | - Yuyu Xie
- Wenzhou Key Laboratory of Biophysics, Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, Zhejiang 325000, P. R. China
| | - Yunlong Zhou
- Wenzhou Key Laboratory of Biophysics, Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, Zhejiang 325000, P. R. China
| | - Xiaoqing Gao
- Wenzhou Key Laboratory of Biophysics, Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, Zhejiang 325000, P. R. China
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2
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Liu C, Zhang S, Hao H, Algaidi H, Ma Y, Zhang XX. Magnetic Skyrmions above Room Temperature in a van der Waals Ferromagnet Fe 3 GaTe 2. Adv Mater 2024:e2311022. [PMID: 38290153 DOI: 10.1002/adma.202311022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2023] [Revised: 01/11/2024] [Indexed: 02/01/2024]
Abstract
2D van der Waals (vdW) ferromagnetic crystals are a promising platform for innovative spintronic devices based on magnetic skyrmions, thanks to their high flexibility and atomic thickness stability. However, room-temperature skyrmion-hosting vdW materials are scarce, which poses a challenge for practical applications. In this study, a chemical vapor transport (CVT) approach is employed to synthesize Fe3 GaTe2 crystals and room-temperature Néel skyrmions are observed in Fe3 GaTe2 nanoflakes above 58 nm in thickness through in situ Lorentz transmission electron microscopy (L-TEM). Upon an optimized field cooling procedure, zero-field hexagonal skyrmion lattices are successfully generated in nanoflakes with an extended thickness range (30-180 nm). Significantly, these skyrmion lattices remain stable up to 355 K, setting a new record for the highest temperature at which skyrmions can be hosted. The research establishes Fe3 GaTe2 as an emerging above-room-temperature skyrmion-hosting vdW material, holding great promise for future spintronics.
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Affiliation(s)
- Chen Liu
- Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Senfu Zhang
- Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
- Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou, 730000, China
| | - Hongyuan Hao
- Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou, 730000, China
| | - Hanin Algaidi
- Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Yinchang Ma
- Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Xi-Xiang Zhang
- Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
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3
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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. Adv Mater 2024:e2312013. [PMID: 38270245 DOI: 10.1002/adma.202312013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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 Fe3 GaTe2 (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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4
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Liu C, Wang J, He W, Zhang C, Zhang S, Yuan S, Hou Z, Qin M, Xu Y, Gao X, Peng Y, Liu K, Qiu ZQ, Liu JM, Zhang X. Strain-Induced Reversible Motion of Skyrmions at Room Temperature. ACS Nano 2024; 18:761-769. [PMID: 38127497 DOI: 10.1021/acsnano.3c09090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2023]
Abstract
Magnetic skyrmions are topologically protected swirling spin textures with great potential for future spintronic applications. The ability to induce skyrmion motion using mechanical strain not only stimulates the exploration of exotic physics but also affords the opportunity to develop energy-efficient spintronic devices. However, the experimental realization of strain-driven skyrmion motion remains a formidable challenge. Herein, we demonstrate that the inhomogeneous uniaxial compressive strain can induce the movement of isolated skyrmions from regions of high strain to regions of low strain at room temperature, which was directly observed using an in situ Lorentz transmission electron microscope with a specially designed nanoindentation holder. We discover that the uniaxial compressive strain can transform skyrmions into a single domain with in-plane magnetization, resulting in the coexistence of skyrmions with a single domain along the direction of the strain gradient. Through comprehensive micromagnetic simulations, we reveal that the repulsive interactions between skyrmions and the single domain serve as the driving force behind the skyrmion motion. The precise control of skyrmion motion through strain provides exciting opportunities for designing advanced spintronic devices that leverage the intricate interplay between strain and magnetism.
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Affiliation(s)
- Chen Liu
- Physical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
- Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou 730000, P. R. China
| | - Junlin Wang
- School of Integrated Circuits, Guangdong University of Technology, Guangzhou 510006, China
- School of Physics, Engineering and Technology, University of York, York YO10 5DD, U.K
| | - Wa He
- Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou 730000, P. R. China
| | - Chenhui Zhang
- Physical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Senfu Zhang
- Physical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
- Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou 730000, P. R. China
| | - Shuai Yuan
- School of Mechanical and Electrical Engineering, Guilin University of Electronic Technology, Guilin 541004, P. R. China
| | - Zhipeng Hou
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
| | - Minghui Qin
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
| | - Yongbing Xu
- School of Integrated Circuits, Guangdong University of Technology, Guangzhou 510006, China
- School of Physics, Engineering and Technology, University of York, York YO10 5DD, U.K
| | - Xingsen Gao
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
| | - Yong Peng
- Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou 730000, P. R. China
| | - Kai Liu
- Physics Department, Georgetown University, Washington, D.C. 20057, United States
| | - Zi Qiang Qiu
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
| | - Jun-Ming Liu
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
- Laboratory of Solid State Microstructures and Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 211102, P. R. China
| | - Xixiang Zhang
- Physical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
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5
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Xu T, Zhang Y, Wang Z, Bai H, Song C, Liu J, Zhou Y, Je SG, N'Diaye AT, Im MY, Yu R, Chen Z, Jiang W. Systematic Control of Ferrimagnetic Skyrmions via Composition Modulation in Pt/Fe 1-xTb x/Ta Multilayers. ACS Nano 2023; 17:7920-7928. [PMID: 37010987 DOI: 10.1021/acsnano.3c02006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Magnetic skyrmions are topological spin textures that can be used as memory and logic components for advancing the next generation spintronics. In this regard, control of nanoscale skyrmions, including their sizes and densities, is of particular importance for enhancing the storage capacity of skyrmionic devices. Here, we propose a viable route for engineering ferrimagnetic skyrmions via tuning the magnetic properties of the involved ferrimagnets Fe1-xTbx. Via tuning the composition of Fe1-xTbx that alters the magnetic anisotropy and the saturation magnetization, the size of the ferrimagnetic skyrmion (ds) and the average density (ηs) can be effectively tailored in [Pt/Fe1-xTbx/Ta]10 multilayers. In particular, a stabilization of sub-50 nm skyrmions with a high density is demonstrated at room temperature. Our work provides an effective approach for designing ferrimagnetic skyrmions with the desired size and density, which could be useful for enabling high-density ferrimagnetic skyrmionics.
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Affiliation(s)
- Teng Xu
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Tsinghua University, Beijing 100084, China
| | - Yuxuan Zhang
- School of Materials Science and Engineering, The State Key Laboratory of New Ceramics and Fine Processing, MOE Key Laboratory of Advanced Materials, Tsinghua University, Beijing 100084, China
| | - Zidong Wang
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Tsinghua University, Beijing 100084, China
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China
| | - Hao Bai
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Tsinghua University, Beijing 100084, China
| | - Chengkun Song
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Tsinghua University, Beijing 100084, China
| | - Jiahao Liu
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Tsinghua University, Beijing 100084, China
| | - Yan Zhou
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China
| | - Soong-Geun Je
- Lawrence Berkeley National Laboratory, Cyclotron Road, Berkeley, California 94720, United States
| | - Alpha T N'Diaye
- Lawrence Berkeley National Laboratory, Cyclotron Road, Berkeley, California 94720, United States
| | - Mi-Young Im
- Lawrence Berkeley National Laboratory, Cyclotron Road, Berkeley, California 94720, United States
| | - Rong Yu
- School of Materials Science and Engineering, The State Key Laboratory of New Ceramics and Fine Processing, MOE Key Laboratory of Advanced Materials, Tsinghua University, Beijing 100084, China
| | - Zhen Chen
- School of Materials Science and Engineering, The State Key Laboratory of New Ceramics and Fine Processing, MOE Key Laboratory of Advanced Materials, Tsinghua University, Beijing 100084, China
| | - Wanjun Jiang
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Tsinghua University, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
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6
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Klose C, Büttner F, Hu W, Mazzoli C, Litzius K, Battistelli R, Lemesh I, Bartell JM, Huang M, Günther CM, Schneider M, Barbour A, Wilkins SB, Beach GSD, Eisebitt S, Pfau B. Coherent correlation imaging for resolving fluctuating states of matter. Nature 2023; 614:256-61. [PMID: 36653456 DOI: 10.1038/s41586-022-05537-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 11/08/2022] [Indexed: 01/19/2023]
Abstract
Fluctuations and stochastic transitions are ubiquitous in nanometre-scale systems, especially in the presence of disorder. However, their direct observation has so far been impeded by a seemingly fundamental, signal-limited compromise between spatial and temporal resolution. Here we develop coherent correlation imaging (CCI) to overcome this dilemma. Our method begins by classifying recorded camera frames in Fourier space. Contrast and spatial resolution emerge by averaging selectively over same-state frames. Temporal resolution down to the acquisition time of a single frame arises independently from an exceptionally low misclassification rate, which we achieve by combining a correlation-based similarity metric1,2 with a modified, iterative hierarchical clustering algorithm3,4. We apply CCI to study previously inaccessible magnetic fluctuations in a highly degenerate magnetic stripe domain state with nanometre-scale resolution. We uncover an intricate network of transitions between more than 30 discrete states. Our spatiotemporal data enable us to reconstruct the pinning energy landscape and to thereby explain the dynamics observed on a microscopic level. CCI massively expands the potential of emerging high-coherence X-ray sources and paves the way for addressing large fundamental questions such as the contribution of pinning5-8 and topology9-12 in phase transitions and the role of spin and charge order fluctuations in high-temperature superconductivity13,14.
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7
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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 Lett 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] [What about the content of this article? (0)] [Affiliation(s)] [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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8
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One RA, Mican S, CimpoesȖu AG, Joldos M, Tetean R, Tiușan CV. Micromagnetic Design of Skyrmionic Materials and Chiral Magnetic Configurations in Patterned Nanostructures for Neuromorphic and Qubit Applications. Nanomaterials (Basel) 2022; 12:4411. [PMID: 36558263 PMCID: PMC9782460 DOI: 10.3390/nano12244411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 12/02/2022] [Accepted: 12/06/2022] [Indexed: 06/17/2023]
Abstract
Our study addresses the problematics of magnetic skyrmions, nanometer-size vortex-like swirling topological defects, broadly studied today for applications in classic, neuromorphic and quantum information technologies. We tackle some challenging issues of material properties versus skyrmion stability and manipulation within a multiple-scale modeling framework, involving complementary ab-initio and micromagnetic frameworks. Ab-initio calculations provide insight into the anatomy of the magnetic anisotropy, the Dzyaloshinskii-Moriya asymmetric exchange interaction (DMI) and their response to a gating electric field. Various multi-layered heterostructures were specially designed to provide electric field tunable perpendicular magnetization and sizeable DMI, which are required for skyrmion occurrence. Landau-Lifshitz-Gilbert micromagnetic calculations in nanometric disks allowed the extraction of material parameter phase diagrams in which magnetic textures were classified according to their topological charge. We identified suitable ranges of magnetic anisotropy, DMI and saturation magnetization for stabilizing skyrmionic ground states or writing/manipulating them using either a spin-transfer torque of a perpendicular current or the electric field. From analyzing the different contributions to the total magnetic free energy, we point out some critical properties influencing the skyrmions' stability. Finally, we discuss some experimental issues related to the choice of materials or the design of novel magnetic materials compatible with skyrmionic applications.
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Affiliation(s)
- Roxana-Alina One
- Department of Condensed Matter Physics and Advanced Technologies, Faculty of Physics, Babeș-Bolyai University of Cluj-Napoca, 400084 Cluj-Napoca, Romania
| | - Sever Mican
- Department of Condensed Matter Physics and Advanced Technologies, Faculty of Physics, Babeș-Bolyai University of Cluj-Napoca, 400084 Cluj-Napoca, Romania
| | - Angela-Georgiana CimpoesȖu
- Department of Condensed Matter Physics and Advanced Technologies, Faculty of Physics, Babeș-Bolyai University of Cluj-Napoca, 400084 Cluj-Napoca, Romania
| | - Marius Joldos
- Computer Science Department, Faculty of Automation and Computer Science, Technical University of Cluj-Napoca, 400027 Cluj-Napoca, Romania
| | - Romulus Tetean
- Department of Condensed Matter Physics and Advanced Technologies, Faculty of Physics, Babeș-Bolyai University of Cluj-Napoca, 400084 Cluj-Napoca, Romania
| | - Coriolan Viorel Tiușan
- Department of Condensed Matter Physics and Advanced Technologies, Faculty of Physics, Babeș-Bolyai University of Cluj-Napoca, 400084 Cluj-Napoca, Romania
- National Center of Scientific Research, 54500 Vandoeuvre-lès-Nancy, France
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9
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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 Lett 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] [What about the content of this article? (0)] [Affiliation(s)] [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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10
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Birch MT, Powalla L, Wintz S, Hovorka O, Litzius K, Loudon JC, Turnbull LA, Nehruji V, Son K, Bubeck C, Rauch TG, Weigand M, Goering E, Burghard M, Schütz G. History-dependent domain and skyrmion formation in 2D van der Waals magnet Fe 3GeTe 2. Nat Commun 2022; 13:3035. [PMID: 35641499 PMCID: PMC9156682 DOI: 10.1038/s41467-022-30740-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 05/16/2022] [Indexed: 11/16/2022] Open
Abstract
The discovery of two-dimensional magnets has initiated a new field of research, exploring both fundamental low-dimensional magnetism, and prospective spintronic applications. Recently, observations of magnetic skyrmions in the 2D ferromagnet Fe3GeTe2 (FGT) have been reported, introducing further application possibilities. However, controlling the exhibited magnetic state requires systematic knowledge of the history-dependence of the spin textures, which remains largely unexplored in 2D magnets. In this work, we utilise real-space imaging, and complementary simulations, to determine and explain the thickness-dependent magnetic phase diagrams of an exfoliated FGT flake, revealing a complex, history-dependent emergence of the uniformly magnetised, stripe domain and skyrmion states. The results show that the interplay of the dominant dipolar interaction and strongly temperature dependent out-of-plane anisotropy energy terms enables the selective stabilisation of all three states at zero field, and at a single temperature, while the Dzyaloshinksii-Moriya interaction must be present to realise the observed Néel-type domain walls. The findings open perspectives for 2D devices incorporating topological spin textures. Fe3GeTe2, known as FGT, is a van der Waals magnetic material that was recently shown to host magnetic skyrmions. Here, Birch et al using both X-ray and electron microscopy to study the stability of skyrmions in FGT, revealing how the sample history can influence skyrmion formation
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Affiliation(s)
- M T Birch
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany.
| | - L Powalla
- Max Planck Institute for Solid State Research, 70569, Stuttgart, Germany.
| | - S Wintz
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - O Hovorka
- Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, SO17 1BJ, UK
| | - K Litzius
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - J C Loudon
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, CB3 0FS, UK
| | - L A Turnbull
- Department of Physics, Durham University, Durham, DH1 3LE, UK
| | - V Nehruji
- Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, SO17 1BJ, UK
| | - K Son
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany.,Department of Physics Education, Kongju National University, Gongju, 32588, South Korea
| | - C Bubeck
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - T G Rauch
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Institut Nanospektroskopie, 12489, Berlin, Germany
| | - M Weigand
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Institut Nanospektroskopie, 12489, Berlin, Germany
| | - E Goering
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - M Burghard
- Max Planck Institute for Solid State Research, 70569, Stuttgart, Germany
| | - G Schütz
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
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11
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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. Sci Adv 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] [What about the content of this article? (0)] [Affiliation(s)] [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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12
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Wang W, Song D, Wei W, Nan P, Zhang S, Ge B, Tian M, Zang J, Du H. Electrical manipulation of skyrmions in a chiral magnet. Nat Commun 2022; 13:1593. [PMID: 35332156 DOI: 10.1038/s41467-022-29217-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 03/03/2022] [Indexed: 11/13/2022] Open
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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13
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Hou Z, Wang Y, Lan X, Li S, Wan X, Meng F, Hu Y, Fan Z, Feng C, Qin M, Zeng M, Zhang X, Liu X, Fu X, Yu G, Zhou G, Zhou Y, Zhao W, Gao X, Liu JM. Controlled Switching of the Number of Skyrmions in a Magnetic Nanodot by Electric Fields. Adv Mater 2022; 34:e2107908. [PMID: 34969153 DOI: 10.1002/adma.202107908] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Revised: 12/18/2021] [Indexed: 06/14/2023]
Abstract
Magnetic skyrmions are topological swirling spin configurations that hold promise for building future magnetic memories and logic circuits. Skyrmionic devices typically rely on the electrical manipulation of a single skyrmion, but controllably manipulating a group of skyrmions can lead to more compact and memory-efficient devices. Here, an electric-field-driven cascading transition of skyrmion clusters in a nanostructured ferromagnetic/ferroelectric multiferroic heterostructure is reported, which allows a continuous multilevel transition of the number of skyrmions in a one-by-one manner. Most notably, the transition is non-volatile and reversible, which is crucial for multi-bit memory applications. Combined experiments and theoretical simulations reveal that the switching of skyrmion clusters is induced by the strain-mediated modification of both the interfacial Dzyaloshinskii-Moriya interaction and effective uniaxial anisotropy. The results not only open up a new direction for constructing low-power-consuming, non-volatile, and multi-bit skyrmionic devices, but also offer valuable insights into the fundamental physics underlying the voltage manipulation of skyrmion clusters.
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Affiliation(s)
- Zhipeng Hou
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, P. R. China
| | - Yadong Wang
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, P. R. China
| | - Xiaoming Lan
- School of Materials Science and Engineering, Dongguan University of Technology, Dongguan, 523808, P. R. China
| | - Sai Li
- Fert Beijing Institute, School of Integrated Circuit Science and Engineering, Beihang University, Beijing, 100191, P. R. China
| | - Xuejin Wan
- School of Materials Science and Engineering, Dongguan University of Technology, Dongguan, 523808, P. R. China
| | - Fei Meng
- Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Yangfan Hu
- School of Materials Science and Engineering, Dongguan University of Technology, Dongguan, 523808, P. R. China
| | - Zhen Fan
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, P. R. China
| | - Chun Feng
- Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Minghui Qin
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, P. R. China
| | - Min Zeng
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, P. R. China
| | - Xichao Zhang
- Department of Electrical and Computer Engineering, Shinshu University, 4-17-1 Wakasato, Nagano, 380-8553, Japan
| | - Xiaoxi Liu
- Department of Electrical and Computer Engineering, Shinshu University, 4-17-1 Wakasato, Nagano, 380-8553, Japan
| | - Xuewen Fu
- Ultrafast Electron Microscopy Laboratory, School of Physics, Nankai University, Tianjin, 300071, P. R. China
| | - Guanghua Yu
- Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Guofu Zhou
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, P. R. China
| | - Yan Zhou
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong, 518172, P. R. China
| | - Weisheng Zhao
- Fert Beijing Institute, School of Integrated Circuit Science and Engineering, Beihang University, Beijing, 100191, P. R. China
| | - Xingsen Gao
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, P. R. China
| | - Jun-Ming Liu
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, P. R. China
- Laboratory of Solid State Microstructures and Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 211102, P. R. China
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14
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Chen X, Lin M, Kong JF, Tan HR, Tan AK, Je S, Tan HK, Khoo KH, Im M, Soumyanarayanan A. Unveiling the Emergent Traits of Chiral Spin Textures in Magnetic Multilayers. Adv Sci (Weinh) 2022; 9:e2103978. [PMID: 34978165 PMCID: PMC8867163 DOI: 10.1002/advs.202103978] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Indexed: 05/16/2023]
Abstract
Magnetic skyrmions are topologically wound nanoscale textures of spins whose ambient stability and electrical manipulation in multilayer films have led to an explosion of research activities. While past efforts focused predominantly on isolated skyrmions, recently ensembles of chiral spin textures, consisting of skyrmions and magnetic stripes, are shown to possess rich interactions with potential for device applications. However, several fundamental aspects of chiral spin texture phenomenology remain to be elucidated, including their domain wall (DW) structure, thermodynamic stability, and morphological transitions. Here the evolution of these textural characteristics are unveiled on a tunable multilayer platform-wherein chiral interactions governing spin texture energetics can be widely varied-using a combination of full-field electron and soft X-ray microscopies with numerical simulations. With increasing chiral interactions, the emergence of Néel helicity, followed by a marked reduction in domain compressibility, and finally a transformation in the skyrmion formation mechanism are demonstrated. Together with an analytical model, these experiments establish a comprehensive microscopic framework for investigating and tailoring chiral spin texture character in multilayer films.
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Affiliation(s)
- Xiaoye Chen
- Institute of Materials Research & EngineeringAgency for ScienceTechnology & Research (A*STAR)Singapore138634Singapore
- Data Storage InstituteAgency for ScienceTechnology & Research (A*STAR)Singapore138634Singapore
| | - Ming Lin
- Institute of Materials Research & EngineeringAgency for ScienceTechnology & Research (A*STAR)Singapore138634Singapore
| | - Jian Feng Kong
- Institute of High Performance ComputingAgency for ScienceTechnology & Research (A*STAR)Singapore138632Singapore
| | - Hui Ru Tan
- Institute of Materials Research & EngineeringAgency for ScienceTechnology & Research (A*STAR)Singapore138634Singapore
| | - Anthony K.C. Tan
- Data Storage InstituteAgency for ScienceTechnology & Research (A*STAR)Singapore138634Singapore
| | - Soong‐Geun Je
- Center for X‐Ray OpticsLawrence Berkeley National LaboratoryBerkeleyCA94720USA
| | - Hang Khume Tan
- Institute of Materials Research & EngineeringAgency for ScienceTechnology & Research (A*STAR)Singapore138634Singapore
- Data Storage InstituteAgency for ScienceTechnology & Research (A*STAR)Singapore138634Singapore
| | - Khoong Hong Khoo
- Institute of High Performance ComputingAgency for ScienceTechnology & Research (A*STAR)Singapore138632Singapore
| | - Mi‐Young Im
- Center for X‐Ray OpticsLawrence Berkeley National LaboratoryBerkeleyCA94720USA
| | - Anjan Soumyanarayanan
- Institute of Materials Research & EngineeringAgency for ScienceTechnology & Research (A*STAR)Singapore138634Singapore
- Data Storage InstituteAgency for ScienceTechnology & Research (A*STAR)Singapore138634Singapore
- Department of PhysicsNational University of SingaporeSingapore117551Singapore
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15
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Kandukuri S, Murthy VSN, Thiruvikraman PK. Isolated skyrmion, skyrmion lattice and antiskyrmion lattice creation through magnetization reversal in Co/Pd nanostructure. Sci Rep 2021; 11:18945. [PMID: 34556719 PMCID: PMC8460664 DOI: 10.1038/s41598-021-98337-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Accepted: 08/30/2021] [Indexed: 11/09/2022] Open
Abstract
Skyrmion and antiskyrmion spin textures are axisymmetric inhomogeneous localized objects with distinct chirality in magnetic systems. These spin textures are potential candidates for the next generation energy-efficient spintronic applications due to their unique topological properties. Controlled and effective creation of the spin textures is required to use in conventional and neuromorphic computing applications. Here we show by micromagnetic simulations creating an isolated skyrmion, skyrmion lattice and antiskyrmion lattice through the magnetization reversal in Co/Pd multilayer nanostructure using spin-polarized current. The spin textures' stability depends on the spin-polarized current density, current pulse width, and Dzyaloshinskii-Moriya interaction (DMI). Antiskyrmions are evolved during the formation of a single skyrmion and skyrmion lattice. Skyrmion and antiskyrmion lattices together are observed for lower pulse width, 0.05 ns. Our micromagnetic studies suggest that the two distinct lattice phases' evolution could help to design the topological spin textures-based devices.
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Affiliation(s)
- Sateesh Kandukuri
- Department of Physics, BITS Pilani Hyderabad Campus, Jawahar Nagar, Kapra Mandal, Medchal District, Hyderabad, 500078, Telangana, India
| | - V Satya Narayana Murthy
- Department of Physics, BITS Pilani Hyderabad Campus, Jawahar Nagar, Kapra Mandal, Medchal District, Hyderabad, 500078, Telangana, India.
| | - P K Thiruvikraman
- Department of Physics, BITS Pilani Hyderabad Campus, Jawahar Nagar, Kapra Mandal, Medchal District, Hyderabad, 500078, Telangana, India
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16
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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. Adv Sci (Weinh) 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] [What about the content of this article? (0)] [Affiliation(s)] [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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17
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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. Adv Mater 2021; 33:e2101610. [PMID: 34224181 DOI: 10.1002/adma.202101610] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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18
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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. Phys Rev Lett 2021; 126:077202. [PMID: 33666484 DOI: 10.1103/physrevlett.126.077202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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19
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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 Lett 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] [What about the content of this article? (0)] [Affiliation(s)] [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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20
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Büttner F, Pfau B, Böttcher M, Schneider M, Mercurio G, Günther CM, Hessing P, Klose C, Wittmann A, Gerlinger K, Kern LM, Strüber C, von Korff Schmising C, Fuchs J, Engel D, Churikova A, Huang S, Suzuki D, Lemesh I, Huang M, Caretta L, Weder D, Gaida JH, Möller M, Harvey TR, Zayko S, Bagschik K, Carley R, Mercadier L, Schlappa J, Yaroslavtsev A, Le Guyarder L, Gerasimova N, Scherz A, Deiter C, Gort R, Hickin D, Zhu J, Turcato M, Lomidze D, Erdinger F, Castoldi A, Maffessanti S, Porro M, Samartsev A, Sinova J, Ropers C, Mentink JH, Dupé B, Beach GSD, Eisebitt S. Observation of fluctuation-mediated picosecond nucleation of a topological phase. Nat Mater 2021; 20:30-37. [PMID: 33020615 DOI: 10.1038/s41563-020-00807-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 08/20/2020] [Indexed: 06/11/2023]
Abstract
Topological states of matter exhibit fascinating physics combined with an intrinsic stability. A key challenge is the fast creation of topological phases, which requires massive reorientation of charge or spin degrees of freedom. Here we report the picosecond emergence of an extended topological phase that comprises many magnetic skyrmions. The nucleation of this phase, followed in real time via single-shot soft X-ray scattering after infrared laser excitation, is mediated by a transient topological fluctuation state. This state is enabled by the presence of a time-reversal symmetry-breaking perpendicular magnetic field and exists for less than 300 ps. Atomistic simulations indicate that the fluctuation state largely reduces the topological energy barrier and thereby enables the observed rapid and homogeneous nucleation of the skyrmion phase. These observations provide fundamental insights into the nature of topological phase transitions, and suggest a path towards ultrafast topological switching in a wide variety of materials through intermediate fluctuating states.
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Affiliation(s)
- Felix Büttner
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Helmholtz-Zentrum für Materialien und Energie GmbH, Berlin, Germany.
| | | | - Marie Böttcher
- Institut für Physik, Johannes Gutenberg Universität Mainz, Mainz, Germany
| | | | | | - Christian M Günther
- Zentraleinrichtung Elektronenmikroskopie (ZELMI), Technische Universität Berlin, Berlin, Germany
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Berlin, Germany
| | | | | | - Angela Wittmann
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | | | | | | | | | | | | | - Alexandra Churikova
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Siying Huang
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Daniel Suzuki
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Ivan Lemesh
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Mantao Huang
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Lucas Caretta
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | | | - John H Gaida
- 4th Physical Institute, University of Göttingen, Göttingen, Germany
| | - Marcel Möller
- 4th Physical Institute, University of Göttingen, Göttingen, Germany
| | - Tyler R Harvey
- 4th Physical Institute, University of Göttingen, Göttingen, Germany
| | - Sergey Zayko
- 4th Physical Institute, University of Göttingen, Göttingen, Germany
| | - Kai Bagschik
- Deutsches Elektronen-Synchrotron (DESY), Hamburg, Germany
| | | | | | | | | | | | | | | | | | | | | | - Jun Zhu
- European XFEL, Schenefeld, Germany
| | | | | | - Florian Erdinger
- Institute of Computer Engineering, Heidelberg University, Heidelberg, Germany
| | - Andrea Castoldi
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano, Italy
- Istituto Nazionale di Fisica Nucleare, Sezione di Milano, Milano, Italy
| | | | | | | | - Jairo Sinova
- Institut für Physik, Johannes Gutenberg Universität Mainz, Mainz, Germany
| | - Claus Ropers
- 4th Physical Institute, University of Göttingen, Göttingen, Germany
| | - Johan H Mentink
- Institute for Molecules and Materials, Radboud University, Nijmegen, the Netherlands
| | - Bertrand Dupé
- Institut für Physik, Johannes Gutenberg Universität Mainz, Mainz, Germany
- Nanomat/Q-mat/CESAM, Université de Liège, Belgium and Fonds de la Recherche Scientifique (FNRS), Bruxelles, Belgium
| | - Geoffrey S D Beach
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Stefan Eisebitt
- Max-Born-Institut, Berlin, Germany
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Berlin, Germany
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21
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Ognev AV, Kolesnikov AG, Kim YJ, Cha IH, Sadovnikov AV, Nikitov SA, Soldatov IV, Talapatra A, Mohanty J, Mruczkiewicz M, Ge Y, Kerber N, Dittrich F, Virnau P, Kläui M, Kim YK, Samardak AS. Magnetic Direct-Write Skyrmion Nanolithography. ACS Nano 2020; 14:14960-14970. [PMID: 33152236 DOI: 10.1021/acsnano.0c04748] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Magnetic skyrmions are stable spin textures with quasi-particle behavior and attract significant interest in fundamental and applied physics. The metastability of magnetic skyrmions at zero magnetic field is particularly important to enable, for instance, a skyrmion racetrack memory. Here, the results of the nucleation of stable skyrmions and formation of ordered skyrmion lattices by magnetic force microscopy in (Pt/CoFeSiB/W)n multilayers, exploiting the additive effect of the interfacial Dzyaloshinskii-Moriya interaction, are presented. The appropriate conditions under which skyrmion lattices are confined with a dense two-dimensional liquid phase are identified. A crucial parameter to control the skyrmion lattice characteristics and the number of scans resulting in the complete formation of a skyrmion lattice is the distance between two adjacent scanning lines of a magnetic force microscopy probe. The creation of skyrmion patterns with complex geometry is demonstrated, and the physical mechanism of direct magnetic writing of skyrmions is comprehended by micromagnetic simulations. This study shows a potential of a direct-write (maskless) skyrmion (topological) nanolithography with sub-100 nm resolution, where each skyrmion acts as a pixel in the final topological image.
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Affiliation(s)
- A V Ognev
- School of Natural Sciences, Far Eastern Federal University, Vladivostok 690950, Russia
| | - A G Kolesnikov
- School of Natural Sciences, Far Eastern Federal University, Vladivostok 690950, Russia
| | - Yong Jin Kim
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea
| | - In Ho Cha
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea
| | - A V Sadovnikov
- Laboratory "Metamaterials", Saratov State University, Saratov 410012, Russia
- Kotel'nikov Institute of Radioengineering and Electronics, Russian Academy of Sciences, Moscow 125009, Russia
| | - S A Nikitov
- Laboratory "Metamaterials", Saratov State University, Saratov 410012, Russia
- Kotel'nikov Institute of Radioengineering and Electronics, Russian Academy of Sciences, Moscow 125009, Russia
| | - I V Soldatov
- Leibniz Institute for Solid State and Material Research (IFW-Dresden), Dresden 01069, Germany
- Institute of Natural Sciences and Mathematic, Ural Federal University, Yekaterinburg 620075, Russia
| | - A Talapatra
- Indian Institute of Technology, Hyderabad 502285, India
| | - J Mohanty
- Indian Institute of Technology, Hyderabad 502285, India
| | - M Mruczkiewicz
- Institute of Electrical Engineering, SAS, Bratislava 841 04, Slovakia
- Centre for Advanced Materials Application (CEMEA), Slovak Academy of Sciences, Bratislava 845 11, Slovakia
| | - Y Ge
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Mainz 55128, Germany
| | - N Kerber
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Mainz 55128, Germany
| | - F Dittrich
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Mainz 55128, Germany
| | - P Virnau
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Mainz 55128, Germany
| | - M Kläui
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Mainz 55128, Germany
| | - Young Keun Kim
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea
| | - A S Samardak
- School of Natural Sciences, Far Eastern Federal University, Vladivostok 690950, Russia
- National Research South Ural State University, Chelyabinsk 454080, Russia
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22
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Lo Conte R, Nandy AK, Chen G, Fernandes Cauduro AL, Maity A, Ophus C, Chen Z, N'Diaye AT, Liu K, Schmid AK, Wiesendanger R. Tuning the Properties of Zero-Field Room Temperature Ferromagnetic Skyrmions by Interlayer Exchange Coupling. Nano Lett 2020; 20:4739-4747. [PMID: 32459968 DOI: 10.1021/acs.nanolett.0c00137] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Magnetic materials offer an opportunity to overcome the scalability and energy consumption limits affecting the semiconductor industry. New computational device architectures, such as low-power solid state magnetic logic and memory-in-logic devices, have been proposed which rely on the unique properties of magnetic materials. Magnetic skyrmions, topologically protected quasi-particles, are at the core of many of the newly proposed spintronic devices. Many different materials systems have been shown hosting ferromagnetic skyrmions at room temperature. However, a magnetic field is a key ingredient to stabilize skyrmions, and this is not desirable for applications, due to the poor scalability of active components generating magnetic fields. Here we report the observation of ferromagnetic skyrmions at room temperature and zero magnetic field, stabilized through interlayer exchange coupling (IEC) between a reference magnet and a free magnet. Most importantly, by tuning the strength of the IEC, we are able to tune the skyrmion size and areal density. Our findings are relevant to the development of skyrmion-based spintronic devices suitable for general-use applications which go beyond modern nanoelectronics.
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Affiliation(s)
- Roberto Lo Conte
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, United States
- Department of Physics, University of Hamburg, D-20355 Hamburg, Germany
| | - Ashis K Nandy
- School of Physical Sciences, National Institute of Science Education and Research, HBNI, P.O. Jatni, 752050, Jatni, India
| | - Gong Chen
- Department of Physics, University of California, Davis, California 95616, United States
| | - Andre L Fernandes Cauduro
- National Center for Electron Microscopy, Molecular Foundry - Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Ajanta Maity
- School of Physical Sciences, National Institute of Science Education and Research, HBNI, P.O. Jatni, 752050, Jatni, India
| | - Colin Ophus
- National Center for Electron Microscopy, Molecular Foundry - Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Zhijie Chen
- Physics Department, Georgetown University, Washington, DC 20057, United States
| | - Alpha T N'Diaye
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Kai Liu
- Department of Physics, University of California, Davis, California 95616, United States
- Physics Department, Georgetown University, Washington, DC 20057, United States
| | - Andreas K Schmid
- National Center for Electron Microscopy, Molecular Foundry - Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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23
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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