1
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Zhou Y, Li S, Liang X, Zhou Y. Topological Spin Textures: Basic Physics and Devices. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2312935. [PMID: 38861696 DOI: 10.1002/adma.202312935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 05/24/2024] [Indexed: 06/13/2024]
Abstract
In the face of escalating modern data storage demands and the constraints of Moore's Law, exploring spintronic solutions, particularly the devices based on magnetic skyrmions, has emerged as a promising frontier in scientific research. Since the first experimental observation of skyrmions, topological spin textures have been extensively studied for their great potential as efficient information carriers in spintronic devices. However, significant challenges have emerged alongside this progress. This review aims to synthesize recent advances in skyrmion research while addressing the major issues encountered in the field. Additionally, current research on promising topological spin structures in addition to skyrmions is summarized. Beyond 2D structures, exploration also extends to 1D magnetic solitons and 3D spin textures. In addition, a diverse array of emerging magnetic materials is introduced, including antiferromagnets and 2D van der Waals magnets, broadening the scope of potential materials hosting topological spin textures. Through a systematic examination of magnetic principles, topological categorization, and the dynamics of spin textures, a comprehensive overview of experimental and theoretical advances in the research of topological magnetism is provided. Finally, both conventional and unconventional applications are summarized based on spin textures proposed thus far. This review provides an outlook on future development in applied spintronics.
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Affiliation(s)
- Yuqing Zhou
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong, 518172, China
| | - Shuang Li
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong, 518172, China
| | - Xue Liang
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong, 518172, China
| | - Yan Zhou
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong, 518172, China
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2
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Gopi AK, Srivastava AK, Sharma AK, Chakraborty A, Das S, Deniz H, Ernst A, Hazra BK, Meyerheim HL, Parkin SSP. Thickness-Tunable Zoology of Magnetic Spin Textures Observed in Fe 5GeTe 2. ACS NANO 2024. [PMID: 38315563 PMCID: PMC10883052 DOI: 10.1021/acsnano.3c09602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2024]
Abstract
The family of two-dimensional (2D) van der Waals (vdW) materials provides a playground for tuning structural and magnetic interactions to create a wide variety of spin textures. Of particular interest is the ferromagnetic compound Fe5GeTe2 that we show displays a range of complex spin textures as well as complex crystal structures. Here, using a high-brailliance laboratory X-ray source, we show that the majority (1 × 1) Fe5GeTe2 (FGT5) phase exhibits a structure that was previously considered as being centrosymmetric but rather lacks inversion symmetry. In addition, FGT5 exhibits a minority phase that exhibits a long-range ordered (√3 × √3)-R30° superstructure. This superstructure is highly interesting in that it is innately 2D without any lattice periodicity perpendicular to the vdW layers, and furthermore, the superstructure is a result of ordered Te vacancies in one of the topmost layers of the FGT5 sheets rather than being a result of vertical Fe ordering as earlier suggested. We show, from direct real-space magnetic imaging, evidence for three distinct magnetic ground states in lamellae of FGT5 that are stabilized with increasing lamella thickness, namely, a multidomain state, a stripe phase, and an unusual fractal state. In the stripe phase we also observe unconventional type-I and type-II bubbles where the spin texture in the central region of the bubbles is nonuniform, unlike conventional bubbles. In addition, we find a bobber or a cocoon-like spin texture in thick (∼170 μm) FGT5 that emerges from the fractal state in the presence of a magnetic field. Among all the 2D vdW magnets we have thus demonstrated that FGT5 hosts perhaps the richest variety of magnetic phases that, thereby, make it a highly interesting platform for the subtle tuning of magnetic interactions.
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Affiliation(s)
- Ajesh K Gopi
- Max Planck Institute of Microstructure Physics, Weinberg 2, Halle (Saale) D-06120, Germany
| | - Abhay K Srivastava
- Max Planck Institute of Microstructure Physics, Weinberg 2, Halle (Saale) D-06120, Germany
| | - Ankit K Sharma
- Max Planck Institute of Microstructure Physics, Weinberg 2, Halle (Saale) D-06120, Germany
| | - Anirban Chakraborty
- Max Planck Institute of Microstructure Physics, Weinberg 2, Halle (Saale) D-06120, Germany
| | - Souvik Das
- Max Planck Institute of Microstructure Physics, Weinberg 2, Halle (Saale) D-06120, Germany
| | - Hakan Deniz
- Max Planck Institute of Microstructure Physics, Weinberg 2, Halle (Saale) D-06120, Germany
| | - Arthur Ernst
- Johannes Kepler University, Altenbergerstraβe 69, Linz 4040, Austria
| | - Binoy K Hazra
- Max Planck Institute of Microstructure Physics, Weinberg 2, Halle (Saale) D-06120, Germany
| | - Holger L Meyerheim
- Max Planck Institute of Microstructure Physics, Weinberg 2, Halle (Saale) D-06120, Germany
| | - Stuart S P Parkin
- Max Planck Institute of Microstructure Physics, Weinberg 2, Halle (Saale) D-06120, Germany
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3
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Zhu H, Xiang G, Feng Y, Zhang X. Dynamics of Elliptical Magnetic Skyrmion in Defective Racetrack. NANOMATERIALS (BASEL, SWITZERLAND) 2024; 14:312. [PMID: 38334583 PMCID: PMC10857043 DOI: 10.3390/nano14030312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 02/01/2024] [Accepted: 02/01/2024] [Indexed: 02/10/2024]
Abstract
Recently, it has been reported that the skyrmion Hall effect can be suppressed in an elliptical skyrmion-based device. Given that defects are unavoidable in materials, it is necessary and important to investigate the dynamics of an elliptical skyrmion in a defective racetrack device. In this work, the current-driven dynamics of an elliptical skyrmion in a defective racetrack device are systematically studied using micromagnetic simulations. The system energy analysis reveals that the magnetic parameters of the circular defect play critical roles in determining the type (repulsive or attractive) and the magnitude of the force on the elliptical skyrmion. The simulated trajectories show that the primary motion modes of the elliptical skyrmion in the defective racetrack can be divided into four types, which are dependent on the values of the Dzyaloshinskii-Moriya interaction (DMI) constant Dd, the perpendicular magnetic anisotropy constant Kd, the magnitude of the driving current density J, and the size d of the defect. Further investigation of the motion-mode phases of the skyrmion reveals the synthetic effects of Dd, Kd, J, and d. Finally, the minimum depinning current density J, which linearly depends on the parameters of Dd and Kd, is obtained for a skyrmion completely pinned in the defect. Our findings give insights into the dynamics of an elliptical skyrmion in the presence of a defect with different magnetic parameters in a racetrack device and may be useful for performance enhancement of skyrmion-based racetrack memory devices.
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Affiliation(s)
| | | | | | - Xi Zhang
- College of Physics, Sichuan University, Chengdu 610065, China
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4
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Tang J, Wu Y, Jiang J, Kong L, Liu W, Wang S, Tian M, Du H. Sewing skyrmion and antiskyrmion by quadrupole of Bloch points. Sci Bull (Beijing) 2023; 68:2919-2923. [PMID: 37949740 DOI: 10.1016/j.scib.2023.10.028] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2023] [Revised: 10/15/2023] [Accepted: 10/24/2023] [Indexed: 11/12/2023]
Affiliation(s)
- Jin Tang
- School of Physics and Optoelectronic Engineering, Anhui University, Hefei 230601, China; Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China.
| | - Yaodong Wu
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
| | - Jialiang Jiang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
| | - Lingyao Kong
- School of Physics and Optoelectronic Engineering, Anhui University, Hefei 230601, China
| | - Wei Liu
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, 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
- School of Physics and Optoelectronic Engineering, Anhui University, Hefei 230601, China; Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
| | - Haifeng Du
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China.
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5
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Jin Z, Yao X, Wang Z, Yuan HY, Zeng Z, Wang W, Cao Y, Yan P. Nonlinear Topological Magnon Spin Hall Effect. PHYSICAL REVIEW LETTERS 2023; 131:166704. [PMID: 37925727 DOI: 10.1103/physrevlett.131.166704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 04/03/2023] [Accepted: 09/15/2023] [Indexed: 11/07/2023]
Abstract
When a magnon passes through two-dimensional magnetic textures, it will experience a fictitious magnetic field originating from the 3×3 skew-symmetric gauge fields. To date, only one of the three independent components of the gauge fields has been found to play a role in generating the fictitious magnetic field, while the other two are perfectly hidden. In this Letter, we show that they are concealed in the nonlinear magnon transport in magnetic textures. Without loss of generality, we theoretically study the nonlinear magnon-skyrmion interaction in antiferromagnets. By analyzing the scattering features of three-magnon processes between the circularly polarized incident magnon and breathing skyrmion, we predict a giant Hall angle of both the confluence and splitting modes. Furthermore, we find that the Hall angle reverses its sign when one switches the handedness of the incident magnons. We dub this the nonlinear topological magnon spin Hall effect. Our findings are deeply rooted in the bosonic nature of magnons that the particle number is not conserved, which has no counterpart in low-energy fermionic systems and may open the door for probing gauge fields by nonlinear means.
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Affiliation(s)
- Zhejunyu Jin
- School of Physics and State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Xianglong Yao
- School of Physics and State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Zhenyu Wang
- School of Physics and State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - H Y Yuan
- Institute for Theoretical Physics, Utrecht University, 3584 CC Utrecht, Netherlands
| | - Zhaozhuo Zeng
- School of Physics and State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Weiwei Wang
- Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, China
| | - Yunshan Cao
- School of Physics and State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Peng Yan
- School of Physics and State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
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6
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Mazzola F, Zhang Y, Olszowska N, Rosmus M, D’Olimpio G, Istrate MC, Politano GG, Vobornik I, Sankar R, Ghica C, Gao J, Politano A. Fermiology of Chiral Cadmium Diarsenide CdAs 2, a Candidate for Hosting Kramers-Weyl Fermions. J Phys Chem Lett 2023; 14:3120-3125. [PMID: 36952263 PMCID: PMC10084463 DOI: 10.1021/acs.jpclett.3c00005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Accepted: 03/20/2023] [Indexed: 06/18/2023]
Abstract
Nonmagnetic chiral crystals are a new class of systems hosting Kramers-Weyl Fermions, arising from the combination of structural chirality, spin-orbit coupling (SOC), and time-reversal symmetry. These materials exhibit nontrivial Fermi surfaces with SOC-induced Chern gaps over a wide energy range, leading to exotic transport and optical properties. In this study, we investigate the electronic structure and transport properties of CdAs2, a newly reported chiral material. We use synchrotron-based angle-resolved photoelectron spectroscopy (ARPES) and density functional theory (DFT) to determine the Fermiology of the (110)-terminated CdAs2 crystal. Our results, together with complementary magnetotransport measurements, suggest that CdAs2 is a promising candidate for novel topological properties protected by the structural chirality of the system. Our work sheds light on the details of the Fermi surface and topology for this chiral quantum material, providing useful information for engineering novel spintronic and optical devices based on quantized chiral charges, negative longitudinal magnetoresistance, and nontrivial Chern numbers.
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Affiliation(s)
- Federico Mazzola
- Istituto
Officina dei Materiali (IOM)−CNR, Laboratorio TASC, Area
Science Park, S.S.14, km 163.5, I-34149 Trieste, Italy
- Department
of Molecular Sciences and Nanosystems, Ca’
Foscari University of Venice, I-30172 Venice, Italy
| | - Yanxue Zhang
- Key
Laboratory of Materials Modification by Laser, Ion and Electron Beams,
Ministry of Education, School of Physics, Dalian University of Technology, Dalian 116024, China
| | - Natalia Olszowska
- National
Synchrotron Radiation Centre SOLARIS, Jagiellonian
University, Czerwone Maki 98, PL-30392 Kraków, Poland
| | - Marcin Rosmus
- National
Synchrotron Radiation Centre SOLARIS, Jagiellonian
University, Czerwone Maki 98, PL-30392 Kraków, Poland
| | - Gianluca D’Olimpio
- Department
of Physical and Chemical Sciences, University
of L’Aquila, via
Vetoio, I-67100 L’Aquila (AQ), Italy
| | | | - Grazia Giuseppina Politano
- Department
of Information Engineering, Infrastructures and Sustainable Energy
(DIIES), University “Mediterranea”
of Reggio Calabria, Loc. Feo di Vito, I-89122 Reggio Calabria, Italy
| | - Ivana Vobornik
- Istituto
Officina dei Materiali (IOM)−CNR, Laboratorio TASC, Area
Science Park, S.S.14, km 163.5, I-34149 Trieste, Italy
| | - Raman Sankar
- Institute
of Physics, Academia Sinica Nankang, Taipei 11529, Taiwan
| | - Corneliu Ghica
- National
Institute of Materials Physics, Atomistilor 405A, 077125 Magurele, Romania
| | - Junfeng Gao
- Key
Laboratory of Materials Modification by Laser, Ion and Electron Beams,
Ministry of Education, School of Physics, Dalian University of Technology, Dalian 116024, China
| | - Antonio Politano
- Department
of Physical and Chemical Sciences, University
of L’Aquila, via
Vetoio, I-67100 L’Aquila (AQ), Italy
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7
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Li L, Song D, Wang W, Zheng F, Kovács A, Tian M, Dunin-Borkowski RE, Du H. Transformation from Magnetic Soliton to Skyrmion in a Monoaxial Chiral Magnet. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2209798. [PMID: 36573473 DOI: 10.1002/adma.202209798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 12/17/2022] [Indexed: 06/18/2023]
Abstract
Topological spin textures are of great interest for both fundamental physics and applications in spintronics. The Dzyaloshinskii-Moriya interaction underpins the formation of single-twisted magnetic solitons or multi-twisted magnetic skyrmions in magnetic materials with different crystallographic symmetries. However, topological transitions between these two kinds of topological objects have not been verified experimentally. Here, the direct observation of transformations from a chiral soliton lattice (CSL) to magnetic skyrmions in a nanostripe of the monoaxial chiral magnet CrNb3 S6 using Lorentz transmission electron microscopy is reported. In the presence of an external magnetic field, helical spin structures first transform into CSLs and then evolve into isolated elongated magnetic skyrmions. The detailed spin textures of the elongated magnetic skyrmions are resolved using off-axis electron holography and are shown to comprise two merons, which enclose their ends and have unit total topological charge. Magnetic dipolar interactions are shown to play a key role in the magnetic soliton-skyrmion transformation, which depends sensitively on nanostripe width. The findings here, which are consistent with micromagnetic simulations, enrich the family of topological magnetic states and their transitions and promise to further stimulate the exploration of their emergent electromagnetic properties.
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Affiliation(s)
- Long Li
- Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei, Anhui, 230031, P. R. China
- Science Island Branch of Graduate School, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China
| | - Dongsheng Song
- Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei, Anhui, 230031, P. R. China
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of Education, Institutes of Physical Science and Information Technology, Anhui University, Hefei, Anhui, 230601, P. R. China
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Weiwei Wang
- Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei, Anhui, 230031, P. R. China
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of Education, Institutes of Physical Science and Information Technology, Anhui University, Hefei, Anhui, 230601, P. R. China
| | - Fengshan Zheng
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425, Jülich, Germany
- Spin-X Institute, Electron Microscopy Center, School of Physics and Optoelectronics, State Key Laboratory of Luminescent Materials and Devices, Guangdong-Hong Kong-Macao Joint Laboratory of Optoelectronic and Magnetic Functional Materials, South China University of Technology, Guangzhou, 510006, P. R. China
| | - András Kovács
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Mingliang Tian
- Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei, Anhui, 230031, P. R. China
- Science Island Branch of Graduate School, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China
- School of Physics and Optoelectronics Engineering, Anhui University, Hefei, Anhui, 230601, P. R. China
| | - Rafal E Dunin-Borkowski
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Haifeng Du
- Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei, Anhui, 230031, P. R. China
- Science Island Branch of Graduate School, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of Education, Institutes of Physical Science and Information Technology, Anhui University, Hefei, Anhui, 230601, P. R. China
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8
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Criado JC, Schenk S, Spannowsky M, Hatton PD, Turnbull LA. Simulating anti-skyrmions on a lattice. Sci Rep 2022; 12:19179. [DOI: 10.1038/s41598-022-22043-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 10/07/2022] [Indexed: 11/11/2022] Open
Abstract
AbstractMagnetic skyrmions are meta-stable spin structures that naturally emerge in magnetic materials. While a vast amount of effort has gone into the study of their properties, their counterpart of opposite topological charge, the anti-skyrmion, has not received as much attention. We aim to close this gap by deploying Monte Carlo simulations of spin-lattice systems in order to investigate which interactions support anti-skyrmions, as well as skyrmions of Bloch and Néel type. We find that the combination of ferromagnetic exchange and Dzyaloshinskii–Moriya (DM) interactions is able to stabilize each of the three types, depending on the specific structure of the DM interactions. Considering a three-dimensional spin lattice model, we provide a finite-temperature phase diagram featuring a stable anti-skyrmion lattice phase for a large range of temperatures. In addition, we also shed light on the creation and annihilation processes of these anti-skyrmion tubes and study the effects of the DM interaction strength on their typical size.
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9
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Real-space determination of the isolated magnetic skyrmion deformation under electric current flow. Proc Natl Acad Sci U S A 2022; 119:e2200958119. [PMID: 36191237 PMCID: PMC9564101 DOI: 10.1073/pnas.2200958119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The manipulation and control of electron spins, the fundamental building blocks of magnetic domains and spin textures, are at the core of spintronics. Of particular interest is the effect of the electric current on topological magnetic skyrmions, such as the current-induced deformation of isolated skyrmions. The deformation has consequences ranging from perturbed dynamics to modified packing configurations. In this study, we measured the current-driven real-space deformation of isolated, pinned skyrmions within Co10Zn10 at room temperature. We observed that the skyrmions are surprisingly soft, readily deforming during electric current application into an elliptical shape with a well-defined deformation axis (semimajor axis). We found that this axis rotates unidirectionally toward the current direction irrespective of electric current polarity and that the elliptical deformation reverses back upon current termination. We quantified the average distortion δ, which increased by ∼90% during the largest applied current density |j| = 8.46 ×109 A/m2 when compared with the skyrmion's intrinsic shape ([Formula: see text]). Additionally, we demonstrated an approximately 120% average skyrmion core size expansion during current application, highlighting the skyrmions' inherent topological protection. This evaluation of in situ electric current-induced skyrmion deformation paints a clearer picture of spin-polarized electron-skyrmion interactions and may prove essential in designing spintronic devices.
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10
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Zhang C, Liu C, Zhang S, Zhou B, Guan C, Ma Y, Algaidi H, Zheng D, Li Y, He X, Zhang J, Li P, Hou Z, Yin G, Liu K, Peng Y, Zhang XX. Magnetic Skyrmions with Unconventional Helicity Polarization in a Van Der Waals Ferromagnet. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2204163. [PMID: 35975291 DOI: 10.1002/adma.202204163] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 08/10/2022] [Indexed: 06/15/2023]
Abstract
Skyrmion helicity, which defines the spin swirling direction, is a fundamental parameter that may be utilized to encode data bits in future memory devices. Generally, in centrosymmetric ferromagnets, dipole skyrmions with helicity of -π/2 and π/2 are degenerate in energy, leading to equal populations of both helicities. On the other hand, in chiral materials where the Dzyaloshinskii-Moriya interaction (DMI) prevails and the dipolar interaction is negligible, only a preferred helicity is selected by the type of DMI. However, whether there is a rigid boundary between these two regimes remains an open question. Herein, the observation of dipole skyrmions with unconventional helicity polarization in a van der Waals ferromagnet, Fe5- δ GeTe2 , is reported. Combining magnetometry, Lorentz transmission electron microscopy, electrical transport measurements, and micromagnetic simulations, the short-range superstructures in Fe5- δ GeTe2 resulting in a localized DMI contribution, which breaks the degeneracy of the opposite helicities and leads to the helicity polarization, is demonstrated. Therefore, the helicity feature in Fe5- δ GeTe2 is controlled by both the dipolar interaction and DMI that the former leads to Bloch-type skyrmions with helicity of ±π/2 whereas the latter breaks the helicity degeneracy. This work provides new insights into the skyrmion topology in van der Waals materials.
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Affiliation(s)
- Chenhui Zhang
- Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Chen Liu
- Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Senfu Zhang
- Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, School of Physical Science and Technology, Lanzhou University, Lanzhou, 730000, China
| | - Bojian Zhou
- School of Materials and Energy and Electron Microscopy Centre of Lanzhou University, Lanzhou University, Lanzhou, 730000, China
| | - Chaoshuai Guan
- School of Materials and Energy and Electron Microscopy Centre of Lanzhou University, Lanzhou University, Lanzhou, 730000, China
| | - Yinchang Ma
- Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Hanin Algaidi
- Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Dongxing Zheng
- Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Yan Li
- Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Xin He
- Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Junwei Zhang
- School of Materials and Energy and Electron Microscopy Centre of Lanzhou University, Lanzhou University, Lanzhou, 730000, China
| | - Peng Li
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, 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, China
- National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou, 510006, China
| | - Gen Yin
- Physics Department, Georgetown University, Washington, DC, 20057, USA
| | - Kai Liu
- Physics Department, Georgetown University, Washington, DC, 20057, USA
| | - Yong Peng
- School of Materials and Energy and Electron Microscopy Centre of Lanzhou University, Lanzhou University, Lanzhou, 730000, China
| | - 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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11
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Peng L, Iakoubovskii KV, Karube K, Taguchi Y, Tokura Y, Yu X. Formation and Control of Zero-Field Antiskyrmions in Confining Geometries. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2202950. [PMID: 35978271 PMCID: PMC9534945 DOI: 10.1002/advs.202202950] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 07/22/2022] [Indexed: 06/15/2023]
Abstract
Magnetic skyrmions and antiskyrmions have attracted much interest owing to their topological features and spintronic functionalities. In contrast to skyrmions, the generation of antiskyrmions relies on tunning both the magnitude and direction of the external magnetic field. Here, it is reported that antiskyrmions can be efficiently created via quenching and robustly persist at zero field in the Fe1.9 Ni0.9 Pd0.2 P magnet with the S4 -symmetry. It is demonstrated that well-ordered antiskyrmions form in a square lattice in a confining micrometer-scale square geometry, while the antiskyrmion lattice distorts in triangular, circular, or rotated-square geometry; the distortion depends on the relative configuration between sample edges and the two q-vectors arising from the anisotropic Dzyaloshinskii-Moriya interaction, in good agreement with micromagnetic simulations. It is also characterized transformations from antiskyrmions to skyrmions and nontopological bubbles at different directions and values of external field. These results demonstrate a roadmap for generating and controlling antiskyrmions in a confining geometry.
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Affiliation(s)
- Licong Peng
- RIKEN Center for Emergent Matter ScienceWako351‐0198Japan
| | | | - Kosuke Karube
- RIKEN Center for Emergent Matter ScienceWako351‐0198Japan
| | | | - Yoshinori Tokura
- RIKEN Center for Emergent Matter ScienceWako351‐0198Japan
- Department of Applied PhysicsUniversity of TokyoBunkyo‐ku113‐8656Japan
- Tokyo CollegeUniversity of TokyoBunkyo‐ku113‐8656Japan
| | - Xiuzhen Yu
- RIKEN Center for Emergent Matter ScienceWako351‐0198Japan
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12
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Observation of Néel-type skyrmions in acentric self-intercalated Cr 1+δTe 2. Nat Commun 2022; 13:3965. [PMID: 35803924 PMCID: PMC9270380 DOI: 10.1038/s41467-022-31319-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Accepted: 06/14/2022] [Indexed: 11/21/2022] Open
Abstract
Transition-metal dichalcogenides intercalated with 3d-transition metals within the van der Waals (vdW) gaps have been the focus of intense investigations owing to their fascinating structural and magnetic properties. At certain concentrations the intercalated atoms form ordered superstructures that exhibit ferromagnetic or anti-ferromagnetic ordering. Here we show that the self-intercalated compound Cr1+δTe2 with δ ≈ 0.3 exhibits a new, so far unseen, three-dimensionally ordered (2×2×2) superstructure. Furthermore, high resolution X-ray diffraction reveals that there is an asymmetric occupation of the two inequivalent vdW gaps in the unit cell. The structure thus lacks inversion symmetry, which, thereby, allows for chiral non-collinear magnetic nanostructures. Indeed, Néel-type skyrmions are directly observed using Lorentz transmission electron microscopy. The skyrmions are stable within the accessible temperature range (100–200 K) as well as in zero magnetic field. The diameter of the Néel skyrmions increases with lamella thickness and varies with applied magnetic field, indicating the role of long-range dipole fields. Our studies show that self-intercalation in vdW materials is a novel route to the formation of synthetic non-collinear spin textures. Here, Saha et al. show that self-intercalation of e2Cr atoms in CrTe2 create an asymmetry in the number of atoms intercalated in the van der Waals gaps between the layers of CrTe2. This inversion symmetry breaking leads to non-collinear spin-textures and Néel-type magnetic skyrmions over a wide temperature range.
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13
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Bhukta M, Singh BB, Mallick S, Rohart S, Bedanta S. Degenerate skyrmionic states in synthetic antiferromagnets. NANOTECHNOLOGY 2022; 33:385702. [PMID: 35636246 DOI: 10.1088/1361-6528/ac7471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Accepted: 05/29/2022] [Indexed: 06/15/2023]
Abstract
Topological magnetic textures, characterized by integer topological chargeS, are potential candidates in future magnetic logic and memory devices, due to their smaller size and expected low threshold current density for their motion. An essential requirement to stabilize them is the Dzyaloshinskii-Moriya interaction (DMI) which promotes a particular chirality, leading to a unique value ofSin a given material. However, recently coexistence of skyrmions and antiskyrmions, with opposite topological charge, in frustrated ferromagnets has been predicted usingJ1-J2-J3classical Heisenberg model, which opens new perspectives, to use the topological charge as an additional degree of freedom. In this work, we propose another approach of using a synthetic antiferromagnetic system, where one of the ferromagnetic (FM) layer has isotropic and the other FM layer has anisotropic DMI to promote the existence of skyrmions and antiskyrmions, respectively. A frustrated interaction arises due to the coupling between the magnetic textures in the FM layers, which enables the stabilization and coexistence of 6 novel elliptical topological textures.
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Affiliation(s)
- Mona Bhukta
- Laboratory for Nanomagnetism and Magnetic Materials, School of Physical Sciences, National Institute of Science Education and Research (NISER), An OCC of Homi Bhabha National Institute (HBNI), Jatni 752050, India
| | - Braj Bhusan Singh
- Laboratory for Nanomagnetism and Magnetic Materials, School of Physical Sciences, National Institute of Science Education and Research (NISER), An OCC of Homi Bhabha National Institute (HBNI), Jatni 752050, India
| | - Sougata Mallick
- Laboratoire de Physique des Solides, Université Paris-Saclay, CNRS UMR 8502, F-91405 Orsay Cedex, France
| | - Stanislas Rohart
- Laboratoire de Physique des Solides, Université Paris-Saclay, CNRS UMR 8502, F-91405 Orsay Cedex, France
| | - Subhankar Bedanta
- Laboratory for Nanomagnetism and Magnetic Materials, School of Physical Sciences, National Institute of Science Education and Research (NISER), An OCC of Homi Bhabha National Institute (HBNI), Jatni 752050, India
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14
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Jena J, Göbel B, Hirosawa T, Díaz SA, Wolf D, Hinokihara T, Kumar V, Mertig I, Felser C, Lubk A, Loss D, Parkin SSP. Observation of fractional spin textures in a Heusler material. Nat Commun 2022; 13:2348. [PMID: 35487903 PMCID: PMC9054820 DOI: 10.1038/s41467-022-29991-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 04/11/2022] [Indexed: 11/09/2022] Open
Abstract
Recently a zoology of non-collinear chiral spin textures has been discovered, most of which, such as skyrmions and antiskyrmions, have integer topological charges. Here we report the experimental real-space observation of the formation and stability of fractional antiskyrmions and fractional elliptical skyrmions in a Heusler material. These fractional objects appear, over a wide range of temperature and magnetic field, at the edges of a sample, whose interior is occupied by an array of nano-objects with integer topological charges, in agreement with our simulations. We explore the evolution of these objects in the presence of magnetic fields and show their interconversion to objects with integer topological charges. This means the topological charge can be varied continuously. These fractional spin textures are not just another type of skyrmion, but are essentially a new state of matter that emerges and lives only at the boundary of a magnetic system. The coexistence of both integer and fractionally charged spin textures in the same material makes the Heusler family of compounds unique for the manipulation of the real-space topology of spin textures and thus an exciting platform for spintronic and magnonic applications. Skyrmions and anti-skyrmions are magnetic textures that have garnered much interest due to their stability. Here, Jena et al demonstrate the existence of fractional spin textures at the edges of Heusler alloy sample, which can have continuous variable topological charges.
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Affiliation(s)
- Jagannath Jena
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle, Germany
| | - Börge Göbel
- Institute of Physics, Martin Luther University Halle-Wittenberg, 06120, Halle, Germany
| | - Tomoki Hirosawa
- Department of Physics, University of Tokyo, Bunkyo, Tokyo, 113-0033, Japan.,Department of Physics, University of Basel, Klingelberg Strasse 82, 4056, Basel, Switzerland
| | - Sebastián A Díaz
- Department of Physics, University of Basel, Klingelberg Strasse 82, 4056, Basel, Switzerland.,Faculty of Physics, University of Duisburg-Essen, 47057, Duisburg, Germany
| | - Daniel Wolf
- Institute for Solid State Research, IFW Dresden, Helmholtzstrasse 20, 01069, Dresden, Germany
| | - Taichi Hinokihara
- Department of Physics, University of Tokyo, Bunkyo, Tokyo, 113-0033, Japan.,Elements Strategy Initiative Center for Magnetic Materials, National Institute for Materials Science, Tsukuba, Ibaraki, 305-0047, Japan
| | - Vivek Kumar
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, 01187, Dresden, Germany
| | - Ingrid Mertig
- Institute of Physics, Martin Luther University Halle-Wittenberg, 06120, Halle, Germany
| | - Claudia Felser
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, 01187, Dresden, Germany
| | - Axel Lubk
- Institute for Solid State Research, IFW Dresden, Helmholtzstrasse 20, 01069, Dresden, Germany
| | - Daniel Loss
- Department of Physics, University of Basel, Klingelberg Strasse 82, 4056, Basel, Switzerland
| | - Stuart S P Parkin
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle, Germany.
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15
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Spin-orbit enabled all-electrical readout of chiral spin-textures. Nat Commun 2022; 13:1576. [PMID: 35332149 PMCID: PMC8948229 DOI: 10.1038/s41467-022-29237-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 03/01/2022] [Indexed: 11/22/2022] Open
Abstract
Chirality and topology are intimately related fundamental concepts, which are heavily explored to establish spin-textures as potential magnetic bits in information technology. However, this ambition is inhibited since the electrical reading of chiral attributes is highly non-trivial with conventional current perpendicular-to-plane (CPP) sensing devices. Here we demonstrate from extensive first-principles simulations and multiple scattering expansion the emergence of the chiral spin-mixing magnetoresistance (C-XMR) enabling highly efficient all-electrical readout of the chirality and helicity of respectively one- and two-dimensional magnetic states of matter. It is linear with spin-orbit coupling in contrast to the quadratic dependence associated with the unveiled non-local spin-mixing anisotropic MR (X-AMR). Such transport effects are systematized on various non-collinear magnetic states – spin-spirals and skyrmions – and compared to the uncovered spin-orbit-independent multi-site magnetoresistances. Owing to their simple implementation in readily available reading devices, the proposed magnetoresistances offer exciting and decisive ingredients to explore with all-electrical means the rich physics of topological and chiral magnetic objects. One challenge for encoding information in chiral spin textures is how to read the information electrically. Here, Lima Fernandes et al. show that chiral spin textures exhibit a magnetoresistance signature which could allow for efficient electric readout of the chirality and helicity.
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16
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Xu C, Li X, Chen P, Zhang Y, Xiang H, Bellaiche L. Assembling Diverse Skyrmionic Phases in Fe 3 GeTe 2 Monolayers. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2107779. [PMID: 35023226 DOI: 10.1002/adma.202107779] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 01/05/2022] [Indexed: 06/14/2023]
Abstract
Skyrmionic magnetic states are promising in advanced spintronics. This topic is experiencing recent progress in 2D magnets, with, for example, a near 300 K Curie temperature observed in Fe3 GeTe2 . However, despite previous studies reporting skyrmions in Fe3 GeTe2 , such a system remains elusive, since it has been reported to host either Néel-type or Bloch-type textures, while a net Dzyaloshinskii-Moriya interaction (DMI) cannot occur in this compound for symmetry reasons. It is thus desirable to develop an accurate model to deeply understand Fe3 GeTe2 . Here, a newly developed method adopting spin invariants is applied to build a first-principle-based Hamiltonian, which predicts colorful topological defects assembled from the unit of Bloch lines, and reveals the critical role of specific forms of fourth-order interactions in Fe3 GeTe2 . Rather than the DMI, it is the multiple fourth-order interactions, with symmetry and spin-orbit couplings considered, that stabilize both Néel-type and Bloch-type skyrmions, as well as antiskyrmions, without any preference for clockwise versus counterclockwise spin rotation. This study also demonstrates that spin invariants can be used as a general approach to study complex magnetic interactions.
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Affiliation(s)
- Changsong Xu
- Key Laboratory of Computational Physical Sciences (Ministry of Education), Institute of Computational Physical Sciences, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai, 200433, China
- Shanghai Qi Zhi Institute, Shanghai, 200232, China
- Physics Department and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, AR, 72701, USA
| | - Xueyang Li
- Key Laboratory of Computational Physical Sciences (Ministry of Education), Institute of Computational Physical Sciences, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai, 200433, China
- Shanghai Qi Zhi Institute, Shanghai, 200232, China
| | - Peng Chen
- Physics Department and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, AR, 72701, USA
| | - Yun Zhang
- Physics Department and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, AR, 72701, USA
- Department of Physics and Information Technology, Baoji University of Arts and Sciences, Baoji, 721016, China
| | - Hongjun Xiang
- Key Laboratory of Computational Physical Sciences (Ministry of Education), Institute of Computational Physical Sciences, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai, 200433, China
- Shanghai Qi Zhi Institute, Shanghai, 200232, China
| | - Laurent Bellaiche
- Physics Department and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, AR, 72701, USA
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17
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Karube K, Peng L, Masell J, Hemmida M, Krug von Nidda HA, Kézsmárki I, Yu X, Tokura Y, Taguchi Y. Doping Control of Magnetic Anisotropy for Stable Antiskyrmion Formation in Schreibersite (Fe,Ni) 3 P with S 4 symmetry. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2108770. [PMID: 35032408 DOI: 10.1002/adma.202108770] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 01/06/2022] [Indexed: 06/14/2023]
Abstract
Magnetic skyrmions, vortex-like topological spin textures, have attracted much interest in a wide range of research fields from fundamental physics to spintronics applications. Recently, growing attention is also paid to antiskyrmions emerging with opposite topological charge in non-centrosymmetric magnets with D2d or S4 symmetry. In these magnets, complex interplay among anisotropic Dzyaloshinskii-Moriya interaction, uniaxial magnetic anisotropy, and magnetic dipolar interactions generates various magnetic textures. However, the precise role of these magnetic interactions in stabilizing antiskyrmions remains to be elucidated. In this work, the uniaxial magnetic anisotropy of schreibersite (Fe,Ni)3 P with S4 symmetry is controlled by doping and its impact on the stability of antiskyrmions is investigated. The authors' magnetometry study, supported by ferromagnetic resonance spectroscopy, shows that the variation of the Ni content and slight doping with 4d transition metals considerably change the magnetic anisotropy. In particular, doping with Pd induces easy-axis anisotropy, giving rise to formation of antiskyrmions, while a temperature-induced spin reorientation is observed in an Rh-doped compound. In combination with Lorentz transmission electron microscopy and micromagnetic simulations, the stability of antiskyrmion as functions of uniaxial anisotropy and demagnetization energy is quantitatively analyzed, and demonstrated that subtle balance between them is necessary to stabilize the antiskyrmions.
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Affiliation(s)
- Kosuke Karube
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan
| | - Licong Peng
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan
| | - Jan Masell
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan
- Institute of Theoretical Solid State Physics, Karlsruhe Institute of Technology (KIT), Karlsruhe, 76049, Germany
| | - Mamoun Hemmida
- Experimental Physics V, University of Augsburg, Augsburg, 86135, Germany
| | | | - István Kézsmárki
- Experimental Physics V, University of Augsburg, Augsburg, 86135, Germany
| | - Xiuzhen Yu
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan
| | - Yoshinori Tokura
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan
- Department of Applied Physics, University of Tokyo, Bunkyo-ku, 113-8656, Japan
- Tokyo College, University of Tokyo, Bunkyo-ku, 113-8656, Japan
| | - Yasujiro Taguchi
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan
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18
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Seki S, Suzuki M, Ishibashi M, Takagi R, Khanh ND, Shiota Y, Shibata K, Koshibae W, Tokura Y, Ono T. Direct visualization of the three-dimensional shape of skyrmion strings in a noncentrosymmetric magnet. NATURE MATERIALS 2022; 21:181-187. [PMID: 34764432 DOI: 10.1038/s41563-021-01141-w] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 09/23/2021] [Indexed: 05/21/2023]
Abstract
Magnetic skyrmions are topologically stable swirling spin textures that appear as particle-like objects in two-dimensional (2D) systems. Here, utilizing scalar magnetic X-ray tomography under applied magnetic fields, we report the direct visualization of the three-dimensional (3D) shape of individual skyrmion strings in the room-temperature skyrmion-hosting non-centrosymmetric compound Mn1.4Pt0.9Pd0.1Sn. Through the tomographic reconstruction of the 3D distribution of the [001] magnetization component on the basis of transmission images taken at various angles, we identify a skyrmion string running through the entire thickness of the sample, as well as various defect structures, such as the interrupted and Y-shaped strings. The observed point defect may represent the Bloch point serving as an emergent magnetic monopole, as proposed theoretically. Our tomographic approach with a tunable magnetic field paves the way for direct visualization of the structural dynamics of individual skyrmion strings in 3D space, which will contribute to a better understanding of the creation, annihilation and transfer of these topological objects.
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Affiliation(s)
- S Seki
- Department of Applied Physics, University of Tokyo, Tokyo, Japan.
- Institute of Engineering Innovation, University of Tokyo, Tokyo, Japan.
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan.
- PRESTO, Japan Science and Technology Agency (JST), Kawaguchi, Japan.
| | - M Suzuki
- Japan Synchrotron Radiation Research Institute, Sayo, Japan.
- School of Engineering, Kwansei Gakuin University, Sanda, Japan.
| | - M Ishibashi
- Institute for Chemical Research, Kyoto University, Uji, Japan
| | - R Takagi
- Department of Applied Physics, University of Tokyo, Tokyo, Japan
- Institute of Engineering Innovation, University of Tokyo, Tokyo, Japan
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan
- PRESTO, Japan Science and Technology Agency (JST), Kawaguchi, Japan
| | - N D Khanh
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan
| | - Y Shiota
- Institute for Chemical Research, Kyoto University, Uji, Japan
| | - K Shibata
- Institute of Industrial Science, The University of Tokyo, Tokyo, Japan
| | - W Koshibae
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan
| | - Y Tokura
- Department of Applied Physics, University of Tokyo, Tokyo, Japan
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan
- Tokyo College, University of Tokyo, Tokyo, Japan
| | - T Ono
- Institute for Chemical Research, Kyoto University, Uji, Japan.
- Center for Spintronics Research Network, Graduate School of Engineering Science, Osaka University, Toyonaka, Japan.
- Center for Spintronics Research Network, Institute for Chemical Research, Kyoto University, Uji, Japan.
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19
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Affiliation(s)
- Jason S. Kahn
- Department of Chemical Engineering Columbia University New York NY 10027 USA
- Center for Functional Nanomaterials Brookhaven National Laboratory Upton NY 11973 USA
| | - Oleg Gang
- Department of Chemical Engineering Columbia University New York NY 10027 USA
- Department of Applied Physics and Applied Mathematics Columbia University New York NY 10027 USA
- Center for Functional Nanomaterials Brookhaven National Laboratory Upton NY 11973 USA
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20
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Sharma AK, Jena J, Rana KG, Markou A, Meyerheim HL, Mohseni K, Srivastava AK, Kostanoskiy I, Felser C, Parkin SSP. Nanoscale Noncollinear Spin Textures in Thin Films of a D 2d Heusler Compound. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2101323. [PMID: 34218470 DOI: 10.1002/adma.202101323] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Indexed: 06/13/2023]
Abstract
Magnetic nano-objects, namely antiskyrmions and Bloch skyrmions, have been found to coexist in single-crystalline lamellae formed from bulk crystals of inverse tetragonal Heusler compounds with D2d symmetry. Here evidence is shown for magnetic nano-objects in epitaxial thin films of Mn2 RhSn formed by magnetron sputtering. These nano-objects exhibit a wide range of sizes with stability with respect to magnetic field and temperature that is similar to single-crystalline lamellae. However, the nano-objects do not form well-defined arrays, nor is any evidence found for helical spin textures. This is speculated to likely be a consequence of the poorer homogeneity of chemical ordering in the thin films. However, evidence is found for elliptically distorted nano-objects along perpendicular crystallographic directions within the epitaxial films, which is consistent with elliptical Bloch skyrmions observed in single-crystalline lamellae. Thus, these measurements provide strong evidence for the formation of noncollinear spin textures in thin films of Mn2 RhSn. Using these films, it is shown that individual nano-objects can be deleted using a local magnetic field from a magnetic tip and collections of nano-objects can be similarly written. These observations suggest a path toward the use of these objects in thin films with D2d symmetry as magnetic memory elements.
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Affiliation(s)
- Ankit K Sharma
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle, Germany
| | - Jagannath Jena
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle, Germany
| | - Kumari Gaurav Rana
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle, Germany
| | - Anastasios Markou
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187, Dresden, Germany
| | - Holger L Meyerheim
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle, Germany
| | - Katayoon Mohseni
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle, Germany
| | - Abhay K Srivastava
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle, Germany
| | - Ilya Kostanoskiy
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle, Germany
| | - Claudia Felser
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187, Dresden, Germany
| | - Stuart S P Parkin
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle, Germany
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21
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Kahn JS, Gang O. Designer Nanomaterials through Programmable Assembly. Angew Chem Int Ed Engl 2021; 61:e202105678. [PMID: 34128306 DOI: 10.1002/anie.202105678] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Indexed: 11/08/2022]
Abstract
Nanoparticles have long been recognized for their unique properties, leading to exciting potential applications across optics, electronics, magnetism, and catalysis. These specific functions often require a designed organization of particles, which includes the type of order as well as placement and relative orientation of particles of the same or different kinds. DNA nanotechnology offers the ability to introduce highly addressable bonds, tailor particle interactions, and control the geometry of bindings motifs. Here, we discuss how developments in structural DNA nanotechnology have enabled greater control over 1D, 2D, and 3D particle organizations through programmable assembly. This Review focuses on how the use of DNA binding between nanocomponents and DNA structural motifs has progressively allowed the rational formation of prescribed particle organizations. We offer insight into how DNA-based motifs and elements can be further developed to control particle organizations and how particles and DNA can be integrated into nanoscale building blocks, so-called "material voxels", to realize designer nanomaterials with desired functions.
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Affiliation(s)
- Jason S Kahn
- Department of Chemical Engineering, Columbia University, New York, NY, 10027, USA.,Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Oleg Gang
- Department of Chemical Engineering, Columbia University, New York, NY, 10027, USA.,Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY, 10027, USA.,Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY, 11973, USA
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22
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Teixeira AW, Castillo-Sepúlveda S, Rizzi LG, Nunez AS, Troncoso RE, Altbir D, Fonseca JM, Carvalho-Santos VL. Motion-induced inertial effects and topological phase transitions in skyrmion transport. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:265403. [PMID: 33902016 DOI: 10.1088/1361-648x/abfb8c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 04/26/2021] [Indexed: 06/12/2023]
Abstract
When the skyrmion dynamics beyond the particle-like description is considered, this topological structure can deform due to a self-induced field. In this work, we perform Monte Carlo simulations to characterize the skyrmion deformation during its steady movement. In the low-velocity regime, the deformation in the skyrmion shape is quantified by an effective inertial mass, which is related to the dissipative force. When skyrmions move faster, the large self-induced deformation triggers topological transitions. These transitions are characterized by the proliferation of skyrmions and a different total topological charge, which is obtained as a function of the skyrmion velocity. Our findings provide an alternative way to describe the dynamics of a skyrmion that accounts for the deformations of its structure. Furthermore, such motion-induced topological phase transitions make it possible to control the number of ferromagnetic skyrmions through velocity effects.
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Affiliation(s)
- A W Teixeira
- Departamento de Física, Universidade Federal de Viçosa, 36570-900, Viçosa, Brazil
| | - S Castillo-Sepúlveda
- Facultad de Ingeniería, Universidad Autónoma de Chile, Av. Pedro de Valdivia 425, Providencia, Santiago, Chile
| | - L G Rizzi
- Departamento de Física, Universidade Federal de Viçosa, 36570-900, Viçosa, Brazil
| | - A S Nunez
- Departamento de Física, FCFM, CEDENNA, Universidad de Chile, Santiago, Chile
| | - R E Troncoso
- Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - D Altbir
- Departamento de Física, CEDENNA, Universidad de Santiago de Chile, USACH, Santiago, Chile
| | - J M Fonseca
- Departamento de Física, Universidade Federal de Viçosa, 36570-900, Viçosa, Brazil
| | - V L Carvalho-Santos
- Departamento de Física, Universidade Federal de Viçosa, 36570-900, Viçosa, Brazil
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23
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Heigl M, Koraltan S, Vaňatka M, Kraft R, Abert C, Vogler C, Semisalova A, Che P, Ullrich A, Schmidt T, Hintermayr J, Grundler D, Farle M, Urbánek M, Suess D, Albrecht M. Dipolar-stabilized first and second-order antiskyrmions in ferrimagnetic multilayers. Nat Commun 2021; 12:2611. [PMID: 33972515 PMCID: PMC8110839 DOI: 10.1038/s41467-021-22600-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 03/15/2021] [Indexed: 02/03/2023] Open
Abstract
Skyrmions and antiskyrmions are topologically protected spin structures with opposite vorticities. Particularly in coexisting phases, these two types of magnetic quasi-particles may show fascinating physics and potential for spintronic devices. While skyrmions are observed in a wide range of materials, until now antiskyrmions were exclusive to materials with D2d symmetry. In this work, we show first and second-order antiskyrmions stabilized by magnetic dipole-dipole interaction in Fe/Gd-based multilayers. We modify the magnetic properties of the multilayers by Ir insertion layers. Using Lorentz transmission electron microscopy imaging, we observe coexisting antiskyrmions, Bloch skyrmions, and type-2 bubbles and determine the range of material properties and magnetic fields where the different spin objects form and dissipate. We perform micromagnetic simulations to obtain more insight into the studied system and conclude that the reduction of saturation magnetization and uniaxial magnetic anisotropy leads to the existence of this zoo of different spin objects and that they are primarily stabilized by dipolar interaction.
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Affiliation(s)
- Michael Heigl
- Institute of Physics, University of Augsburg, Augsburg, Germany.
| | - Sabri Koraltan
- Faculty of Physics, University of Vienna, Vienna, Austria
| | - Marek Vaňatka
- CEITEC BUT, Brno University of Technology, Brno, Czech Republic
| | - Robert Kraft
- Faculty of Physics, University of Vienna, Vienna, Austria
| | - Claas Abert
- Faculty of Physics, University of Vienna, Vienna, Austria
- Research Platform MMM Mathematics - Magnetism - Materials, University of Vienna, Vienna, Austria
| | | | - Anna Semisalova
- Center for Nanointegration and Faculty of Physics, University of Duisburg-Essen, Duisburg, Germany
| | - Ping Che
- Laboratory of Nanoscale Magnetic Materials and Magnonics, Institute of Materials (IMX), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Aladin Ullrich
- Institute of Physics, University of Augsburg, Augsburg, Germany
| | - Timo Schmidt
- Institute of Physics, University of Augsburg, Augsburg, Germany
| | | | - Dirk Grundler
- Laboratory of Nanoscale Magnetic Materials and Magnonics, Institute of Materials (IMX), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Institute of Microengineering (IMT), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Michael Farle
- Center for Nanointegration and Faculty of Physics, University of Duisburg-Essen, Duisburg, Germany
| | - Michal Urbánek
- CEITEC BUT, Brno University of Technology, Brno, Czech Republic
| | - Dieter Suess
- Faculty of Physics, University of Vienna, Vienna, Austria
- Research Platform MMM Mathematics - Magnetism - Materials, University of Vienna, Vienna, Austria
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24
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Cui B, Yu D, Shao Z, Liu Y, Wu H, Nan P, Zhu Z, Wu C, Guo T, Chen P, Zhou HA, Xi L, Jiang W, Wang H, Liang S, Du H, Wang KL, Wang W, Wu K, Han X, Zhang G, Yang H, Yu G. Néel-Type Elliptical Skyrmions in a Laterally Asymmetric Magnetic Multilayer. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2006924. [PMID: 33599001 DOI: 10.1002/adma.202006924] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 01/10/2021] [Indexed: 06/12/2023]
Abstract
Magnetic skyrmions, topological-chiral spin textures, have potential applications in next-generation high-density and energy-efficient spintronic devices for information storage and logic technologies. Tailoring the detailed spin textures of skyrmions is of pivotal importance for tuning skyrmion dynamics, which is one of the key factors for the design of skyrmionic devices. Here, the direct observation of parallel aligned elliptical magnetic skyrmions in Pt/Co/Ta multilayers with an oblique-angle deposited Co layer is reported. Domain wall velocity and spin-orbit-torque-induced out-of-plane effective field analysis demonstrate that the formation of unusual elliptical skyrmions is correlated to the anisotropic effective perpendicular magnetic anisotropy energy density (Keff u ) and Dzyaloshinskii-Moriya interaction (DMI) in the film plane. Structural analysis and first-principles calculations further show that the anisotropic Keff u and DMI originate from the interfacial anisotropic strain introduced by the oblique-angle deposition. The work provides a method to tune the spin textures of skyrmions in magnetic multilayers and, thereby, a new degree of freedom for the design of skyrmionic devices.
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Affiliation(s)
- Baoshan Cui
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Dongxing Yu
- Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, China
| | - Ziji Shao
- Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, China
| | - Yizhou Liu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan
| | - Hao Wu
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA, 90095, USA
| | - Pengfei Nan
- Institutes of Physical Science and Information Technology, Anhui University, Hefei, 230601, China
| | - Zengtai Zhu
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Chuangwen Wu
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
- Faculty of Physics and Electronic Science, Hubei University, Wuhan, 430062, China
| | - Tengyu Guo
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - Peng Chen
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - Heng-An Zhou
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing, 100084, China
| | - Li Xi
- Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, School of Physical Science and Technology, Lanzhou University, Lanzhou, 730000, China
| | - Wanjun Jiang
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing, 100084, China
| | - Hao Wang
- Faculty of Physics and Electronic Science, Hubei University, Wuhan, 430062, China
| | - Shiheng Liang
- Faculty of Physics and Electronic Science, Hubei University, Wuhan, 430062, 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
| | - Kang L Wang
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA, 90095, USA
| | - Wenhong Wang
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Kehui Wu
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Xiufeng Han
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Guangyu Zhang
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Hongxin Yang
- Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, China
| | - Guoqiang Yu
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
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25
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Karube K, Peng L, Masell J, Yu X, Kagawa F, Tokura Y, Taguchi Y. Room-temperature antiskyrmions and sawtooth surface textures in a non-centrosymmetric magnet with S 4 symmetry. NATURE MATERIALS 2021; 20:335-340. [PMID: 33495630 DOI: 10.1038/s41563-020-00898-w] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 12/02/2020] [Indexed: 06/12/2023]
Abstract
Topological spin textures have attracted much attention both for fundamental physics and spintronics applications. Among them, antiskyrmions possess a unique spin configuration with Bloch-type and Néel-type domain walls owing to anisotropic Dzyaloshinskii-Moriya interaction in the non-centrosymmetric crystal structure. However, antiskyrmions have thus far only been observed in a few Heusler compounds with D2d symmetry. Here we report a new material, Fe1.9Ni0.9Pd0.2P, in a different symmetry class (S4), in which antiskyrmions exist over a wide temperature range that includes room temperature, and transform into skyrmions on changing magnetic field and lamella thickness. The periodicity of magnetic textures greatly depends on the crystal thickness, and domains with anisotropic sawtooth fractals were observed at the surface of thick crystals and attributed to the interplay between the dipolar interaction and the Dzyaloshinskii-Moriya interaction as governed by crystal symmetry. Our findings provide an arena in which to study antiskyrmions, and should stimulate further research on topological spin textures and their applications.
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Affiliation(s)
- Kosuke Karube
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan.
| | - Licong Peng
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan
| | - Jan Masell
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan
| | - Xiuzhen Yu
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan
| | - Fumitaka Kagawa
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan
- Department of Applied Physics, University of Tokyo, Bunkyo-ku, Japan
| | - Yoshinori Tokura
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan
- Department of Applied Physics, University of Tokyo, Bunkyo-ku, Japan
- Tokyo College, University of Tokyo, Bunkyo-ku, Japan
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26
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Göbel B, Mertig I. Skyrmion ratchet propagation: utilizing the skyrmion Hall effect in AC racetrack storage devices. Sci Rep 2021; 11:3020. [PMID: 33542288 PMCID: PMC7862652 DOI: 10.1038/s41598-021-81992-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 01/14/2021] [Indexed: 11/23/2022] Open
Abstract
Magnetic skyrmions are whirl-like nano-objects with topological protection. When driven by direct currents, skyrmions move but experience a transverse deflection. This so-called skyrmion Hall effect is often regarded a drawback for memory applications. Herein, we show that this unique effect can also be favorable for spintronic applications: We show that in a racetrack with a broken inversion symmetry, the skyrmion Hall effect allows to translate an alternating current into a directed motion along the track, like in a ratchet. We analyze several modes of the ratchet mechanism and show that it is unique for topological magnetic whirls. We elaborate on the fundamental differences compared to the motion of topologically trivial magnetic objects, as well as classical particles driven by periodic forces. Depending on the exact racetrack geometry, the ratchet mechanism can be soft or strict. In the latter case, the skyrmion propagates close to the efficiency maximum.
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Affiliation(s)
- Börge Göbel
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, 06099, Halle (Saale), Germany.
| | - Ingrid Mertig
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, 06099, Halle (Saale), Germany
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27
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Jena J, Göbel B, Kumar V, Mertig I, Felser C, Parkin S. Evolution and competition between chiral spin textures in nanostripes with D 2d symmetry. SCIENCE ADVANCES 2020; 6:6/49/eabc0723. [PMID: 33277247 PMCID: PMC7821896 DOI: 10.1126/sciadv.abc0723] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Accepted: 10/20/2020] [Indexed: 06/12/2023]
Abstract
Chiral spin textures are of considerable interest for applications in spintronics. It has recently been shown that magnetic materials with D 2d symmetry can sustain several distinct spin textures. Here, we show, using Lorentz transmission electron microscopy, that single and double chains of antiskyrmions can be generated at room temperature in nanostripes less than 0.5 μm in width formed from the D 2d Heusler compound Mn1.4Pt0.9Pd0.1Sn. Typically, truncated helical spin textures are formed in low magnetic fields, whose edges are terminated by half antiskyrmions. These evolve into chains of antiskyrmions with increasing magnetic field. Single chains of these objects are located in the middle of the nanostripes even when the stripes are much wider than the antiskyrmions. Moreover, the chains can even include elliptical Bloch skyrmions depending on details of the applied magnetic field history. These findings make D 2d materials special and highly interesting for applications such as magnetic racetrack memory storage devices.
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Affiliation(s)
- Jagannath Jena
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
| | - Börge Göbel
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
- Institute of Physics, Martin Luther University Halle-Wittenberg, 06099 Halle, Germany
| | - Vivek Kumar
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, 01187 Dresden, Germany
| | - Ingrid Mertig
- Institute of Physics, Martin Luther University Halle-Wittenberg, 06099 Halle, Germany
| | - Claudia Felser
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, 01187 Dresden, Germany
| | - Stuart Parkin
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany.
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28
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Yasin FS, Peng L, Takagi R, Kanazawa N, Seki S, Tokura Y, Yu X. Bloch Lines Constituting Antiskyrmions Captured via Differential Phase Contrast. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e2004206. [PMID: 33043519 DOI: 10.1002/adma.202004206] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 08/11/2020] [Indexed: 06/11/2023]
Abstract
Much scientific capital has been directed toward exotic magnetic spin textures called Bloch lines, that is, Néel-type line boundaries within domain walls, because their geometry promises high-density magnetic storage. While predicted to arise in high-anisotropy magnets, bulk soft magnets, and thin films with in-plane magnetization, Bloch lines also constitute magnetic antiskyrmions, that is, topological antiparticles of skyrmions. Most domain walls occur as Bloch-type or Néel-type, in which the magnetization rotates parallel or perpendicular to the domain wall across its profile, respectively. The Bloch lines' Néel-type rotation and their minute size make them difficult to directly measure. This work utilizes differential phase contrast (DPC) scanning transmission electron microscopy (STEM) to measure the in-plane magnetization of Bloch lines within antiskyrmions emergent in a non-centrosymmetric Heusler magnet with D2d symmetry, Mn1.4 Pt0.9 Pd0.1 Sn, in addition to Bloch-type skyrmions in an FeGe magnet with B20-type crystal structure to benchmark the DPC technique. Both in-focus measurement and identification of Bloch lines at the antiskyrmion's corners are provided.
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Affiliation(s)
- Fehmi S Yasin
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan
| | - Licong Peng
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan
| | - Rina Takagi
- Institute of Engineering Innovation, The University of Tokyo, Tokyo, 113-0032, Japan
- Department of Applied Physics, The University of Tokyo, Tokyo, 113-8656, Japan
| | - Naoya Kanazawa
- Department of Applied Physics, The University of Tokyo, Tokyo, 113-8656, Japan
| | - Shinichiro Seki
- Institute of Engineering Innovation, The University of Tokyo, Tokyo, 113-0032, Japan
- Department of Applied Physics, The University of Tokyo, Tokyo, 113-8656, Japan
| | - Yoshinori Tokura
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan
- Department of Applied Physics, The University of Tokyo, Tokyo, 113-8656, Japan
- Tokyo College, University of Tokyo, Tokyo, 113-8656, Japan
| | - Xiuzhen Yu
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan
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29
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Sivakumar P, Göbel B, Lesne E, Markou A, Gidugu J, Taylor JM, Deniz H, Jena J, Felser C, Mertig I, Parkin SSP. Topological Hall Signatures of Two Chiral Spin Textures Hosted in a Single Tetragonal Inverse Heusler Thin Film. ACS NANO 2020; 14:13463-13469. [PMID: 32986403 PMCID: PMC7596786 DOI: 10.1021/acsnano.0c05413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 09/28/2020] [Indexed: 06/11/2023]
Abstract
Magnetic skyrmions and antiskyrmions are observed in material classes with different crystal symmetries, where the Dzyaloshinskii-Moriya interaction stabilizes either skyrmions or antiskyrmions. Here, we report the observation of two distinct peaks in the topological Hall effect in a thin film of Mn2RhSn. Utilizing a phenomenological approach and electronic transport simulations, these topological Hall effect features are attributed to be direct signatures of two topologically distinct chiral spin objects, namely, skyrmions and antiskyrmions. Topological Hall effect studies allow us to determine the existence of these two topological objects over a wide range of temperature and magnetic fields. In particular, we find skyrmions to be stable at low temperatures, suggesting the increased importance of dipolar interactions.
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Affiliation(s)
- Pranava
K. Sivakumar
- Max
Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
| | - Börge Göbel
- Max
Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
- Institute
of Physics, Martin Luther University Halle-Wittenberg, 06099 Halle, Germany
| | - Edouard Lesne
- Max
Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
| | - Anastasios Markou
- Max
Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, 01187 Dresden, Germany
| | - Jyotsna Gidugu
- Max
Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
| | - James M. Taylor
- Max
Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
| | - Hakan Deniz
- Max
Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
| | - Jagannath Jena
- Max
Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
| | - Claudia Felser
- Max
Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, 01187 Dresden, Germany
| | - Ingrid Mertig
- Institute
of Physics, Martin Luther University Halle-Wittenberg, 06099 Halle, Germany
| | - Stuart S. P. Parkin
- Max
Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
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30
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Ma T, Sharma AK, Saha R, Srivastava AK, Werner P, Vir P, Kumar V, Felser C, Parkin SSP. Tunable Magnetic Antiskyrmion Size and Helical Period from Nanometers to Micrometers in a D 2d Heusler Compound. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e2002043. [PMID: 32484269 DOI: 10.1002/adma.202002043] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 04/27/2020] [Indexed: 06/11/2023]
Abstract
Skyrmions and antiskyrmions are magnetic nano-objects with distinct chiral, noncollinear spin textures that are found in various magnetic systems with crystal symmetries that give rise to specific Dzyaloshinskii-Moriya exchange vectors. These magnetic nano-objects are associated with closely related helical spin textures that can form in the same material. The skyrmion size and the period of the helix are generally considered as being determined, in large part, by the ratio of the magnitude of the Heisenberg to that of the Dzyaloshinskii-Moriya exchange interaction. In this work, it is shown by real-space magnetic imaging that the helix period λ and the size of the antiskyrmion daSk in the D2d compound Mn1.4 PtSn can be systematically tuned by more than an order of magnitude from ≈100 nm to more than 1.1 µm by varying the thickness of the lamella in which they are observed. The chiral spin texture is verified to be preserved even up to micrometer-thick layers. This extreme size tunability is shown to arise from long-range magnetodipolar interactions, which typically play a much less important role for B20 skyrmions. This tunability in size makes antiskyrmions very attractive for technological applications.
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Affiliation(s)
- Tianping Ma
- Max Planck Institute of Microstructure Physics, Weinberg 2, Halle (Saale), D-06120, Germany
- Institute of Physics, Martin Luther University, Halle-Wittenberg, Halle (Saale), D-06120, Germany
| | - Ankit K Sharma
- Max Planck Institute of Microstructure Physics, Weinberg 2, Halle (Saale), D-06120, Germany
- Institute of Physics, Martin Luther University, Halle-Wittenberg, Halle (Saale), D-06120, Germany
| | - Rana Saha
- Max Planck Institute of Microstructure Physics, Weinberg 2, Halle (Saale), D-06120, Germany
| | - Abhay K Srivastava
- Max Planck Institute of Microstructure Physics, Weinberg 2, Halle (Saale), D-06120, Germany
- Institute of Physics, Martin Luther University, Halle-Wittenberg, Halle (Saale), D-06120, Germany
| | - Peter Werner
- Max Planck Institute of Microstructure Physics, Weinberg 2, Halle (Saale), D-06120, Germany
| | - Praveen Vir
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straβe 40, Dresden, 01187, Germany
| | - Vivek Kumar
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straβe 40, Dresden, 01187, Germany
| | - Claudia Felser
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straβe 40, Dresden, 01187, Germany
| | - Stuart S P Parkin
- Max Planck Institute of Microstructure Physics, Weinberg 2, Halle (Saale), D-06120, Germany
- Institute of Physics, Martin Luther University, Halle-Wittenberg, Halle (Saale), D-06120, Germany
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