Bulk Spin Torque-Driven Perpendicular Magnetization Switching in L10 FePt Single Layer |
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Authors: | Meng Tang Ka Shen Shijie Xu Huanglin Yang Shuai Hu Weiming Lü Changjian Li Mengsha Li Zhe Yuan Stephen J. Pennycook Ke Xia Aurelien Manchon Shiming Zhou Xuepeng Qiu |
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Affiliation: | 1. Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology School of Physics Science and Engineering, Tongji University, Shanghai, 200092 China;2. Department of Physics, Beijing Normal University, Beijing, 100875 China;3. Spintronics Institute, University of Jinan, Jinan, 250022 China Condensed Matter Science and Technology Institute, School of Science, Harbin Institute of Technology, Harbin, 150081 China;4. Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575 Singapore;5. Beijing Computational Science Research Center, Beijing, 100193 China;6. Division of Physical Science and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955 Saudi Arabia |
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Abstract: | Due to its inherent superior perpendicular magnetocrystalline anisotropy, the FePt in L10 phase enables magnetic storage and memory devices with ultrahigh capacity. However, reversing the FePt magnetic state, and therefore encoding information, has proven to be extremely difficult. Here, it is demonstrated that an electric current can exert a large spin torque on an L10 FePt magnet, ultimately leading to reversible magnetization switching. The spin torque monotonically increases with increasing FePt thickness, exhibiting a bulk characteristic. Meanwhile, the spin torque effective fields and switching efficiency increase as the FePt approaches higher chemical ordering with stronger spin–orbit coupling. The symmetry breaking that generates spin torque within L10 FePt is shown to arise from an inherent structural gradient along the film normal direction. By artificially reversing the structural gradient, an opposite spin torque effect in L10 FePt is demonstrated. At last, the role of the disorder gradient in generating a substantial torque in a single ferromagnet is supported by theoretical calculations. These results will push forward the frontier of material systems for generating spin torques and will have a transformative impact on magnetic storage and spin memory devices with simple architecture, ultrahigh density, and readily application. |
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Keywords: | crystallinity L10 magnetic alloy spin–orbit torques |
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