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Hassan M, Koraltan S, Ullrich A, Bruckner F, Serha RO, Levchenko KV, Varvaro G, Kiselev NS, Heigl M, Abert C, Suess D, Albrecht M. Dipolar skyrmions and antiskyrmions of arbitrary topological charge at room temperature. NATURE PHYSICS 2024; 20:615-622. [PMID: 38638455 PMCID: PMC11021192 DOI: 10.1038/s41567-023-02358-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 11/29/2023] [Indexed: 04/20/2024]
Abstract
Magnetic skyrmions are localized, stable topological magnetic textures that can move and interact with each other like ordinary particles when an external stimulus is applied. The efficient control of the motion of spin textures using spin-polarized currents opened an opportunity for skyrmionic devices such as racetrack memory and neuromorphic or reservoir computing. The coexistence of skyrmions with high topological charge in the same system promises further possibilities for efficient technological applications. In this work, we directly observe dipolar skyrmions and antiskyrmions with arbitrary topological charge in Co/Ni multilayers at room temperature. We explore the dipolar-stabilized spin objects with topological charges of up to 10 and characterize their nucleation process, their energy dependence on the topological charge and the effect of the material parameters on their stability. Furthermore, our micromagnetic simulations demonstrate spin-transfer-induced motion of these spin objects, which is important for their potential device application.
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Affiliation(s)
- Mariam Hassan
- Institute of Physics, University of Augsburg, Augsburg, Germany
- ISM – CNR, nM2-Lab, Monterotondo Scalo, Roma, Italy
| | - Sabri Koraltan
- Physics of Functional Materials, Faculty of Physics, University of Vienna, Vienna, Austria
- Vienna Doctoral School in Physics, University of Vienna, Vienna, Austria
- Research Platform MMM Mathematics – Magnetism – Materials, University of Vienna, Vienna, Austria
| | - Aladin Ullrich
- Institute of Physics, University of Augsburg, Augsburg, Germany
| | - Florian Bruckner
- Physics of Functional Materials, Faculty of Physics, University of Vienna, Vienna, Austria
| | - Rostyslav O. Serha
- Vienna Doctoral School in Physics, University of Vienna, Vienna, Austria
- Nanomagnetism and Magnonics, Faculty of Physics, University of Vienna, Vienna, Austria
| | | | | | - Nikolai S. Kiselev
- Peter Grünberg Institute and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, Jülich, Germany
| | - Michael Heigl
- Institute of Physics, University of Augsburg, Augsburg, Germany
| | - Claas Abert
- Physics of Functional Materials, Faculty of Physics, University of Vienna, Vienna, Austria
- Research Platform MMM Mathematics – Magnetism – Materials, University of Vienna, Vienna, Austria
| | - Dieter Suess
- Physics of Functional Materials, Faculty of Physics, University of Vienna, Vienna, Austria
- Research Platform MMM Mathematics – Magnetism – Materials, University of Vienna, Vienna, Austria
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Wang XR, Hu XC, Sun ZZ. Topological Equivalence of Stripy States and Skyrmion Crystals. NANO LETTERS 2023; 23:3954-3962. [PMID: 37096810 DOI: 10.1021/acs.nanolett.3c00718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Stripy states, consisting of a collection of stripy spin textures, are the precursors of skyrmion crystals (SkXs). The common belief is that stripy states and SkXs are topologically unconnected and that transitions between SkXs and stripy states are phase transitions. Here, we show that both stripy states and SkXs are skyrmion condensates and they are topologically equivalent. By gradually tuning the stripe whose width goes from smaller than to larger than skyrmion-skyrmion separation, the structure of a skyrmion condensate transforms smoothly and continuously from various stripy phases, including helical states and mazes, to crystals, showing that stripy states are topologically connected to SkXs.
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Affiliation(s)
- X R Wang
- Physics Department, The Hong Kong University of Science and Technology (HKUST), Clear Water Bay, Kowloon, Hong Kong
- HKUST Shenzhen Research Institute, Shenzhen 518057, China
| | - Xu-Chong Hu
- Physics Department, The Hong Kong University of Science and Technology (HKUST), Clear Water Bay, Kowloon, Hong Kong
- HKUST Shenzhen Research Institute, Shenzhen 518057, China
| | - Zhou-Zhou Sun
- HKUST Shenzhen Research Institute, Shenzhen 518057, China
- South China Business College, Guangdong University of Foreign Studies, Guangzhou 510545, China
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