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Lv X, Lv H, Huang Y, Zhang R, Qin G, Dong Y, Liu M, Pei K, Cao G, Zhang J, Lai Y, Che R. Distinct skyrmion phases at room temperature in two-dimensional ferromagnet Fe 3GaTe 2. Nat Commun 2024; 15:3278. [PMID: 38627376 PMCID: PMC11021542 DOI: 10.1038/s41467-024-47579-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 04/03/2024] [Indexed: 04/19/2024] Open
Abstract
Distinct skyrmion phases at room temperature hosted by one material offer additional degree of freedom for the design of topology-based compact and energetically-efficient spintronic devices. The field has been extended to low-dimensional magnets with the discovery of magnetism in two-dimensional van der Waals magnets. However, creating multiple skyrmion phases in 2D magnets, especially above room temperature, remains a major challenge. Here, we report the experimental observation of mixed-type skyrmions, exhibiting both Bloch and hybrid characteristics, in a room-temperature ferromagnet Fe3GaTe2. Analysis of the magnetic intensities under varied imaging conditions coupled with complementary simulations reveal that spontaneous Bloch skyrmions exist as the magnetic ground state with the coexistence of hybrid stripes domain, on account of the interplay between the dipolar interaction and the Dzyaloshinskii-Moriya interaction. Moreover, hybrid skyrmions are created and their coexisting phases with Bloch skyrmions exhibit considerably high thermostability, enduring up to 328 K. The findings open perspectives for 2D spintronic devices incorporating distinct skyrmion phases at room temperature.
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Affiliation(s)
- Xiaowei Lv
- Laboratory of Advanced Materials, Shanghai Key Lab of Molecular Catalysis and Innovative Materials, Academy for Engineering & Technology, Fudan University, Shanghai, 200438, PR China
| | - Hualiang Lv
- Shanghai Frontiers Science Research Base of Intelligent Optoelectronics and Perception, Institute of Optoelectronics, Fudan University, Shanghai, 200433, PR China
| | - Yalei Huang
- Materials Genome Institute, Shanghai University, Shanghai, 200444, China
| | | | - Guanhua Qin
- Zhejiang Laboratory, Hangzhou, 311100, China
| | - Yihui Dong
- Materials Genome Institute, Shanghai University, Shanghai, 200444, China
| | - Min Liu
- Laboratory of Advanced Materials, Shanghai Key Lab of Molecular Catalysis and Innovative Materials, Academy for Engineering & Technology, Fudan University, Shanghai, 200438, PR China
| | - Ke Pei
- Laboratory of Advanced Materials, Shanghai Key Lab of Molecular Catalysis and Innovative Materials, Academy for Engineering & Technology, Fudan University, Shanghai, 200438, PR China
| | - Guixin Cao
- Materials Genome Institute, Shanghai University, Shanghai, 200444, China.
- Zhejiang Laboratory, Hangzhou, 311100, China.
| | | | - Yuxiang Lai
- Pico Electron Microscopy Center, Innovation Institute for Ocean Materials Characterization, Center for Advanced Studies in Precision Instruments, Hainan University, Haikou, 570228, China
| | - Renchao Che
- Laboratory of Advanced Materials, Shanghai Key Lab of Molecular Catalysis and Innovative Materials, Academy for Engineering & Technology, Fudan University, Shanghai, 200438, PR China.
- Zhejiang Laboratory, Hangzhou, 311100, 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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Man P, Huang L, Zhao J, Ly TH. Ferroic Phases in Two-Dimensional Materials. Chem Rev 2023; 123:10990-11046. [PMID: 37672768 DOI: 10.1021/acs.chemrev.3c00170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/08/2023]
Abstract
Two-dimensional (2D) ferroics, namely ferroelectric, ferromagnetic, and ferroelastic materials, are attracting rising interest due to their fascinating physical properties and promising functional applications. A variety of 2D ferroic phases, as well as 2D multiferroics and the novel 2D ferrovalleytronics/ferrotoroidics, have been recently predicted by theory, even down to the single atomic layers. Meanwhile, some of them have already been experimentally verified. In addition to the intrinsic 2D ferroics, appropriate stacking, doping, and defects can also artificially regulate the ferroic phases of 2D materials. Correspondingly, ferroic ordering in 2D materials exhibits enormous potential for future high density memory devices, energy conversion devices, and sensing devices, among other applications. In this paper, the recent research progresses on 2D ferroic phases are comprehensively reviewed, with emphasis on chemistry and structural origin of the ferroic properties. In addition, the promising applications of the 2D ferroics for information storage, optoelectronics, and sensing are also briefly discussed. Finally, we envisioned a few possible pathways for the future 2D ferroics research and development. This comprehensive overview on the 2D ferroic phases can provide an atlas for this field and facilitate further exploration of the intriguing new materials and physical phenomena, which will generate tremendous impact on future functional materials and devices.
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Affiliation(s)
- Ping Man
- Department of Chemistry and Center of Super-Diamond & Advanced Films (COSDAF), City University of Hong Kong, Kowloon, Hong Kong 999077, P. R. China
- City University of Hong Kong Shenzhen Research Institute, Shenzhen 518057, P. R. China
| | - Lingli Huang
- Department of Chemistry and Center of Super-Diamond & Advanced Films (COSDAF), City University of Hong Kong, Kowloon, Hong Kong 999077, P. R. China
- City University of Hong Kong Shenzhen Research Institute, Shenzhen 518057, P. R. China
| | - Jiong Zhao
- Department of Applied Physics, The Hong Kong Polytechnic University, Kowloon, Hong Kong 999077, P. R. China
- The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen 518057, P. R. China
| | - Thuc Hue Ly
- Department of Chemistry and Center of Super-Diamond & Advanced Films (COSDAF), City University of Hong Kong, Kowloon, Hong Kong 999077, P. R. China
- City University of Hong Kong Shenzhen Research Institute, Shenzhen 518057, P. R. China
- Department of Chemistry and State Key Laboratory of Marine Pollution, City University of Hong Kong, Kowloon, Hong Kong 999077, P. R. China
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4
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Pradines B, Cahier B, Suaud N, Guihéry N. Impact of the electric field on isotropic and anisotropic spin Hamiltonian parameters. J Chem Phys 2022; 157:204308. [DOI: 10.1063/5.0116709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
One may obviously think that the best way to control magnetic properties relies on using a magnetic field. However, it is not convenient to focus a magnetic field on a small object, whereas it is much easier to do so with an electric field. Magnetoelectric coupling allows one to control the magnetization with the electric field and the polarization with the magnetic field and could therefore provide a solution to this problem. This paper aims at quantifying the impact of the electric field on both the isotropic magnetic exchange and the Dzyaloshinskii–Moriya interaction in the case of a binuclear system of S = 1/2 spins. This study follows previous studies that showed that very high Dzyaloshinskii–Moriya interaction, i.e., the antisymmetric exchange, can be generated when close to first order spin orbit coupling. We will, therefore, explore this regime in a model Cu(II) complex that exhibits a quasi-degeneracy of the [Formula: see text] and d xy orbitals. This situation is indeed the one that allows us to obtain the largest spin orbit couplings in transition metal complexes. We will show that both the magnetic exchange and the Dzyaloshinskii–Moriya interaction are very sensitive to the electric field and that it would therefore be possible to modulate and control magnetic properties by the electric field. Finally, rationalizations of the obtained results will be proposed.
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Affiliation(s)
- Barthélémy Pradines
- Laboratoire de Chimie et Physique Quantiques, UMR5626, University of Toulouse 3, Paul Sabatier, 18 route de Narbonne, 31062 Toulouse, France
| | - Benjamin Cahier
- Laboratoire de Chimie et Physique Quantiques, UMR5626, University of Toulouse 3, Paul Sabatier, 18 route de Narbonne, 31062 Toulouse, France
| | - Nicolas Suaud
- Laboratoire de Chimie et Physique Quantiques, UMR5626, University of Toulouse 3, Paul Sabatier, 18 route de Narbonne, 31062 Toulouse, France
| | - Nathalie Guihéry
- Laboratoire de Chimie et Physique Quantiques, UMR5626, University of Toulouse 3, Paul Sabatier, 18 route de Narbonne, 31062 Toulouse, France
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5
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Three-dimensional skyrmionic cocoons in magnetic multilayers. Nat Commun 2022; 13:6843. [DOI: 10.1038/s41467-022-34370-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 10/21/2022] [Indexed: 11/13/2022] Open
Abstract
AbstractThree-dimensional spin textures emerge as promising quasi-particles for encoding information in future spintronic devices. The third dimension provides more malleability regarding their properties and more flexibility for potential applications. However, the stabilization and characterization of such quasi-particles in easily implementable systems remain a work in progress. Here we observe a three-dimensional magnetic texture that sits in the interior of magnetic thin films aperiodic multilayers and possesses a characteristic ellipsoidal shape. Interestingly, these objects that we call skyrmionic cocoons can coexist with more standard tubular skyrmions going through all the multilayer as evidenced by the existence of two very different contrasts in room temperature magnetic force microscopy. The presence of these novel skyrmionic textures as well as the understanding of their layer resolved chiral and topological properties have been investigated by micromagnetic simulations. Finally, we show that the skyrmionic cocoons can be electrically detected using magneto-transport measurements.
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6
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Yıldırım O, Tomasello R, Feng Y, Carlotti G, Tacchi S, Vaghefi PM, Giordano A, Dutta T, Finocchio G, Hug HJ, Mandru AO. Tuning the Coexistence Regime of Incomplete and Tubular Skyrmions in Ferromagnetic/Ferrimagnetic/Ferromagnetic Trilayers. ACS APPLIED MATERIALS & INTERFACES 2022; 14:34002-34010. [PMID: 35830277 DOI: 10.1021/acsami.2c06608] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The development of skyrmionic devices requires a suitable tuning of material parameters to stabilize skyrmions and control their density. It has been demonstrated recently that different skyrmion types can be simultaneously stabilized at room temperature in heterostructures involving ferromagnets, ferrimagnets, and heavy metals, offering a new platform of coding binary information in the type of skyrmion instead of the presence/absence of skyrmions. Here, we tune the energy landscape of the two skyrmion types in such heterostructures by engineering the geometrical and material parameters of the individual layers. We find that a fine adjustment of the ferromagnetic layer thickness, and thus its magnetic anisotropy, allows the trilayer system to support either one of the skyrmion types or the coexistence of both and with varying densities.
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Affiliation(s)
- Oğuz Yıldırım
- Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland
| | - Riccardo Tomasello
- Department of Electrical and Information Engineering, Politecnico di Bari, 70125 Bari, Italy
| | - Yaoxuan Feng
- Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland
| | - Giovanni Carlotti
- Dipartimento di Fisica e Geologia, Università di Perugia, 06123 Perugia, Italy
| | - Silvia Tacchi
- Istituto Officina dei Materiali del CNR (CNR-IOM), Sede Secondaria di Perugia, c/o Dipartimento di Fisica e Geologia, Università di Perugia, 06123 Perugia, Italy
| | - Pegah Mirzadeh Vaghefi
- Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland
| | - Anna Giordano
- Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, I-98166 Messina, Italy
| | - Tanmay Dutta
- Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland
| | - Giovanni Finocchio
- Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, I-98166 Messina, Italy
| | - Hans J Hug
- Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland
- Department of Physics, University of Basel, CH-4056 Basel, Switzerland
| | - Andrada-Oana Mandru
- Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland
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7
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Lohmiller T, Spyra CJ, Dechert S, Demeshko S, Bill E, Schnegg A, Meyer F. Antisymmetric Spin Exchange in a μ-1,2-Peroxodicopper(II) Complex with an Orthogonal Cu-O-O-Cu Arrangement and S = 1 Spin Ground State Characterized by THz-EPR. JACS AU 2022; 2:1134-1143. [PMID: 35647586 PMCID: PMC9131480 DOI: 10.1021/jacsau.2c00139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/08/2022] [Accepted: 04/11/2022] [Indexed: 06/15/2023]
Abstract
A unique type of Cu2/O2 adduct with orthogonal (close to 90°) Cu-O-O-Cu arrangement has been proposed for initial stages of O2 binding at biological type III dicopper sites, and targeted ligand design has now allowed us to emulate such an adduct in a pyrazolate-based μ-η1 :η1-peroxodicopper(II) complex (2) with Cu-O-O-Cu torsion φ of 87°, coined ⊥ P intermediate. Full characterization of 2, including X-ray diffraction (d O-O = 1.452 Å) and Raman spectroscopy (ν̃O-O = 807 cm-1), completes a series of closely related Cu2/O2 intermediates featuring μ-η1 :η1-peroxodicopper(II) cores with φ ranging from 55° (A, cis-peroxo C P; Brinkmeier A.et al., J. Am. Chem. Soc.2021, 143, 10361) via 87° (2, ⊥ P type) up to 104° (B, approaching trans-peroxo T P; Kindermann N.et al., Angew. Chem., Int. Ed.2015, 54, 1738). SQUID magnetometry revealed ferromagnetic interaction of the CuII ions and a triplet (S t = 1) ground state in 2. Frequency-domain THz-EPR has been employed to quantitatively investigate the spin systems of 2 and B. Magnetic transitions within the triplet ground states confirmed their substantial zero-field splittings (ZFS) suggested by magnetometry. Formally forbidden triplet-to-singlet transitions at 56 (2) and 157 cm-1 (B), which are in agreement with the exchange coupling strengths J iso inferred from SQUID data, are reported for the first time for coupled dicopper(II) complexes. Rigorous analysis by spin-Hamiltonian-based simulations attributed the corresponding nonzero transition probabilities and the ZFS to substantial antisymmetric (Dzyaloshinskii-Moriya) exchange d and provided robust values and orientations for the d , J , and g tensors. These interactions can be correlated with the Cu-O-O-Cu geometries, revealing a linear increase of J iso with the Cu-O-O-Cu torsion and a strong linear decrease with the Cu-O-O angle. Relevance of the ⊥ P intermediate for O2 activation at type III dicopper sites and a potential role of antisymmetric exchange in the concomitant intersystem crossing are proposed.
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Affiliation(s)
- Thomas Lohmiller
- EPR4Energy
Joint Lab, Department Spins in Energy Conversion and Quantum Information
Science, Helmholtz Zentrum Berlin für
Materialien und Energie GmbH, Albert-Einstein-Straße 16, 12489 Berlin, Germany
| | - Can-Jerome Spyra
- University
of Göttingen, Institute of Inorganic Chemistry, Tamannstrasse 4, D-37077 Göttingen, Germany
| | - Sebastian Dechert
- University
of Göttingen, Institute of Inorganic Chemistry, Tamannstrasse 4, D-37077 Göttingen, Germany
| | - Serhiy Demeshko
- University
of Göttingen, Institute of Inorganic Chemistry, Tamannstrasse 4, D-37077 Göttingen, Germany
| | - Eckhard Bill
- Max
Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, D-45470 Mülheim an der
Ruhr, Germany
| | - Alexander Schnegg
- Max
Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, D-45470 Mülheim an der
Ruhr, Germany
| | - Franc Meyer
- University
of Göttingen, Institute of Inorganic Chemistry, Tamannstrasse 4, D-37077 Göttingen, Germany
- University
of Göttingen, International Center for Advanced Studies of
Energy Conversion (ICASEC), D-37077 Göttingen, Germany
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8
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Wu Y, Francisco B, Chen Z, Wang W, Zhang Y, Wan C, Han X, Chi H, Hou Y, Lodesani A, Yin G, Liu K, Cui YT, Wang KL, Moodera JS. A Van der Waals Interface Hosting Two Groups of Magnetic Skyrmions. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2110583. [PMID: 35218078 DOI: 10.1002/adma.202110583] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 01/26/2022] [Indexed: 06/14/2023]
Abstract
Multiple magnetic skyrmion phases add an additional degree of freedom for skyrmion-based ultrahigh-density spin memory devices. Extending the field to 2D van der Waals magnets is a rewarding challenge, where the realizable degree of freedoms (e.g., thickness, twist angle, and electrical gating) and high skyrmion density result in intriguing new properties and enhanced functionality. In this work, a van der Waals interface, formed by two 2D ferromagnets Cr2 Ge2 Te6 and Fe3 GeTe2 with a Curie temperature of ≈65 and ≈205 K, respectively, hosting two groups of magnetic skyrmions, is reported. Two sets of topological Hall effect signals are observed below 6s0 K when Cr2 Ge2 Te6 is magnetically ordered. These two groups of skyrmions are directly imaged using magnetic force microscopy, and supported by micromagnetic simulations. Interestingly, the magnetic skyrmions persist in the heterostructure with zero applied magnetic field. The results are promising for the realization of skyrmionic devices based on van der Waals heterostructures hosting multiple skyrmion phases.
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Affiliation(s)
- Yingying Wu
- Francis Bitter Magnet Laboratory and Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Brian Francisco
- Department of Physics and Astronomy, University of California, Riverside, CA, 92521, USA
| | - Zhijie Chen
- Department of Physics, Georgetown University, Washington, D.C., 20057, USA
| | - Wei Wang
- Key Laboratory of Flexible Electronics & Institute of Advanced Materials, Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing Tech University, Nanjing, 211816, China
| | - Yu Zhang
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Caihua Wan
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Xiufeng Han
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Hang Chi
- Francis Bitter Magnet Laboratory and Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- U.S. Army CCDC Army Research Laboratory, Adelphi, MD, 20783, USA
| | - Yasen Hou
- Francis Bitter Magnet Laboratory and Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Alessandro Lodesani
- Francis Bitter Magnet Laboratory and Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Gen Yin
- Department of Physics, Georgetown University, Washington, D.C., 20057, USA
| | - Kai Liu
- Department of Physics, Georgetown University, Washington, D.C., 20057, USA
| | - Yong-Tao Cui
- Department of Physics and Astronomy, University of California, Riverside, CA, 92521, USA
| | - Kang L Wang
- Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, CA, 90095, USA
| | - Jagadeesh S Moodera
- Francis Bitter Magnet Laboratory and Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Physics Department, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
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9
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Yu D, Yang H, Chshiev M, Fert A. Skyrmions-based logic gates in one single nanotrack completely reconstructed via chirality barrier. Natl Sci Rev 2022; 9:nwac021. [PMID: 36713589 PMCID: PMC9874028 DOI: 10.1093/nsr/nwac021] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 01/06/2022] [Accepted: 01/07/2022] [Indexed: 02/01/2023] Open
Abstract
Logic gates based on magnetic elements are promising candidates for logic-in-memory applications with non-volatile data retention, near-zero leakage and scalability. In such spin-based logic devices, however, the multi-strip structure and fewer functions are obstacles to improving integration and reducing energy consumption. Here we propose a skyrmions-based single-nanotrack logic family including AND, OR, NOT, NAND, NOR, XOR and XNOR that can be implemented and reconstructed by building and switching the Dzyaloshinskii-Moriya interaction (DMI) chirality barrier on a racetrack memory. Besides the pinning effect of the DMI chirality barrier on skyrmions, the annihilation, fusion and shunting of two skyrmions with opposite chirality are also achieved and demonstrated via local reversal of the DMI, which are necessary for the design of an engineer programmable logic nanotrack, transistor and complementary racetrack memory.
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Affiliation(s)
- Dongxing Yu
- Quantum Functional Materials Laboratory, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
| | | | - Mairbek Chshiev
- Université Grenoble Alpes, CEA, CNRS, Spintec, Grenoble 38000, France,Institut Universitaire de France (IUF), Paris 75231, France
| | - Albert Fert
- Université Paris-Saclay, Unité Mixte de Physique CNRS-Thales, Palaiseau 91767, France
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10
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Bouammali MA, Suaud N, Maurice R, Guihéry N. Extraction of giant Dzyaloshinskii-Moriya interaction from ab initio calculations: First-order spin-orbit coupling model and methodological study. J Chem Phys 2021; 155:164305. [PMID: 34717350 DOI: 10.1063/5.0065213] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The Dzyaloshinskii-Moriya interaction is expected to be at the origin of interesting magnetic properties, such as multiferroicity, skyrmionic states, and exotic spin orders. Despite this, its theoretical determination is far from being established, neither from the point of view of ab initio methodologies nor from that of the extraction technique to be used afterward. Recently, a very efficient way to increase its amplitude has been demonstrated near the first-order spin-orbit coupling regime. Within the first-order regime, the anisotropic spin Hamiltonian involving the Dzyaloshinskii-Moriya operator becomes inappropriate. Nevertheless, in order to approach this regime and identify the spin Hamiltonian limitations, it is necessary to characterize the underlying physics. To this end, we have developed a simple electronic and spin-orbit model describing the first-order regime and used ab initio calculations to conduct a thorough methodological study.
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Affiliation(s)
- Mohammed-Amine Bouammali
- Laboratoire de Chimie et Physique Quantiques, UMR5626, University of Toulouse 3, Paul Sabatier, 18 route de Narbonne, 31062 Toulouse, France
| | - Nicolas Suaud
- Laboratoire de Chimie et Physique Quantiques, UMR5626, University of Toulouse 3, Paul Sabatier, 18 route de Narbonne, 31062 Toulouse, France
| | - Rémi Maurice
- Subatech, UMR CNRS 6457, IN2P3/IMT Atlantique/University of Nantes, 4 rue A. Kastler, 44307 Nantes Cedex 3, France
| | - Nathalie Guihéry
- Laboratoire de Chimie et Physique Quantiques, UMR5626, University of Toulouse 3, Paul Sabatier, 18 route de Narbonne, 31062 Toulouse, France
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11
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A Ti/Pt/Co Multilayer Stack for Transfer Function Based Magnetic Force Microscopy Calibrations. MAGNETOCHEMISTRY 2021. [DOI: 10.3390/magnetochemistry7060078] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Magnetic force microscopy (MFM) is a widespread technique for imaging magnetic structures with a resolution of some 10 nanometers. MFM can be calibrated to obtain quantitative (qMFM) spatially resolved magnetization data in units of A/m by determining the calibrated point spread function of the instrument, its instrument calibration function (ICF), from a measurement of a well-known reference sample. Beyond quantifying the MFM data, a deconvolution of the MFM image data with the ICF also corrects the smearing caused by the finite width of the MFM tip stray field distribution. However, the quality of the calibration depends critically on the calculability of the magnetization distribution of the reference sample. Here, we discuss a Ti/Pt/Co multilayer stack that shows a stripe domain pattern as a suitable reference material. A precise control of the fabrication process, combined with a characterization of the sample micromagnetic parameters, allows reliable calculation of the sample’s magnetic stray field, proven by a very good agreement between micromagnetic simulations and qMFM measurements. A calibrated qMFM measurement using the Ti/Pt/Co stack as a reference sample is shown and validated, and the application area for quantitative MFM measurements calibrated with the Ti/Pt/Co stack is discussed.
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Bouammali MA, Suaud N, Martins C, Maurice R, Guihéry N. How to create giant Dzyaloshinskii-Moriya interactions? Analytical derivation and ab initio calculations on model dicopper(II) complexes. J Chem Phys 2021; 154:134301. [PMID: 33832262 DOI: 10.1063/5.0045569] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
This paper is a theoretical "proof of concept" on how the on-site first-order spin-orbit coupling (SOC) can generate giant Dzyaloshinskii-Moriya interactions in binuclear transition metal complexes. This effective interaction plays a key role in strongly correlated materials, skyrmions, multiferroics, and molecular magnets of promising use in quantum information science and computing. Despite this, its determination from both theory and experiment is still in its infancy and existing systems usually exhibit very tiny magnitudes. We derive analytical formulas that perfectly reproduce both the nature and the magnitude of the Dzyaloshinskii-Moriya interaction calculated using state-of-the-art ab initio calculations performed on model bicopper(II) complexes. We also study which geometrical structures/ligand-field forces would enable one to control the magnitude and the orientation of the Dzyaloshinskii-Moriya vector in order to guide future synthesis of molecules or materials. This article provides an understanding of its microscopic origin and proposes recipes to increase its magnitude. We show that (i) the on-site mixings of 3d orbitals rule the orientation and magnitude of this interaction, (ii) increased values can be obtained by choosing more covalent complexes, and (iii) huge values (∼1000 cm-1) and controlled orientations could be reached by approaching structures exhibiting on-site first-order SOC, i.e., displaying an "unquenched orbital momentum."
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Affiliation(s)
- Mohammed-Amine Bouammali
- Laboratoire de Chimie et Physique Quantiques, UMR5626, Université de Toulouse 3, Paul Sabatier, 118 route de Narbonne, 31062 Toulouse, France
| | - Nicolas Suaud
- Laboratoire de Chimie et Physique Quantiques, UMR5626, Université de Toulouse 3, Paul Sabatier, 118 route de Narbonne, 31062 Toulouse, France
| | - Cyril Martins
- Laboratoire de Chimie et Physique Quantiques, UMR5626, Université de Toulouse 3, Paul Sabatier, 118 route de Narbonne, 31062 Toulouse, France
| | - Rémi Maurice
- SUBATECH, UMR CNRS 6457, IN2P3/IMT Atlantique/Université de Nantes, 4 rue A. Kastler, 44307 Nantes Cedex 3, France
| | - Nathalie Guihéry
- Laboratoire de Chimie et Physique Quantiques, UMR5626, Université de Toulouse 3, Paul Sabatier, 118 route de Narbonne, 31062 Toulouse, France
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Abstract
Skyrmions are chiral swirling magnetization structures with nanoscale size. These structures have attracted considerable attention due to their topological stability and promising applicability in nanodevices, since they can be displaced with spin-polarized currents. However, for the comprehensive implementation of skyrmions in devices, it is imperative to also attain control over their geometrical position. Here we show that, through thickness modulations introduced in the host material, it is possible to constrain three-dimensional skyrmions to desired regions. We investigate skyrmion structures in rectangular FeGe platelets with micromagnetic finite element simulations. First, we establish a phase diagram of the minimum-energy magnetic state as a function of the external magnetic field strength and the film thickness. Using this understanding, we generate preferential sites for skyrmions in the material by introducing dot-like “pockets” of reduced film thickness. We show that these pockets can serve as pinning centers for the skyrmions, thus making it possible to obtain a geometric control of the skyrmion position. This control allows for stabilization of skyrmions at positions and in configurations that they would otherwise not attain. Our findings may have implications for technological applications in which skyrmions are used as units of information that are displaced along racetrack-type shift register devices.
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