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Exchange bias switching in an antiferromagnet/ferromagnet bilayer driven by spin–orbit torque

Nature Electronics volume 3, pages 757–764 (2020)Cite this article

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Abstract

The electrical manipulation of magnetization and exchange bias in antiferromagnet/ferromagnet thin films could be of use in the development of the next generation of spintronic devices. Current-controlled magnetization switching can be driven by spin–orbit torques generated in an adjacent heavy-metal layer, but these structures are difficult to integrate with exchange bias switching and tunnelling magnetoresistance measurements. Here, we report the current-induced switching of the exchange bias field in a perpendicularly magnetized IrMn/CoFeB bilayer structure using a spin–orbit torque generated in the antiferromagnetic IrMn layer. By manipulating the current direction and amplitude, independent and repeatable switching of the magnetization and exchange bias field below the blocking temperature can be achieved. The critical current density for the exchange bias switching is found to be larger than that for CoFeB magnetization reversal. X-ray magnetic circular dichroism, polarized neutron reflectometry measurements and micromagnetic simulations show that a small net magnetization within the IrMn interface plays a crucial role in these phenomena.

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Fig. 1: Magnetic properties of the IrMn/CoFeB/MgO films and the Hall bars.
Fig. 2: Exchange bias and magnetization switching driven by current-induced SOT.
Fig. 3: Bidirectional switching of exchange bias field depending on SOT current polarity.
Fig. 4: XMCD and PNR during switching.
Fig. 5: Micromagnetic simulation results of exchange bias and its manipulation by SOT.
Fig. 6: Temperature and thickness dependence of magnetization and exchange bias switching.

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Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.

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Acknowledgements

We thank the National Natural Science Foundation of China (grant nos. 61627813, 61571023), the International Collaboration Project B16001, the National Key Technology Program of China 2017ZX01032101 and the Beihang Hefei Innovation Research Institute Project BHKX-19-02 for their financial support of this work. This research used resources of the Advanced Light Source, a DOE Office of Science User Facility, under contract no. DE-AC02-05CH11231.

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Author notes

  1. These authors contributed equally: Shouzhong Peng, Daoqian Zhu.

Authors and Affiliations

  1. Fert Beijing Institute, Beijing Advanced Innovation Center for Big Data and Brain Computing, School of Integrated Circuit Science and Engineering, Beihang University, Beijing, China

    Shouzhong Peng, Daoqian Zhu, Weixiang Li, Jiaqi Lu, Danrong Xiong, Wenlong Cai & Weisheng Zhao

  2. Hefei Innovation Research Institute, Beihang University, Hefei, China

    Shouzhong Peng, Weixiang Li, Jiaqi Lu & Weisheng Zhao

  3. Department of Electrical Engineering, University of California, Los Angeles, Los Angeles, CA, USA

    Hao Wu & Kang L. Wang

  4. NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, USA

    Alexander J. Grutter & Dustin A. Gilbert

  5. Materials Science and Engineering, University of Tennessee, Knoxville, TN, USA

    Dustin A. Gilbert

  6. Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, USA

    Padraic Shafer

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Contributions

W.Z. initialized, conceived and supervised the project. S.P. fabricated the devices. S.P., W.L., J.L., W.C. and D.X. performed the measurements. D.Z. performed the micromagnetic simulations. H.W. deposited the thin films under the supervision of K.L.W. A.J.G., D.A.G. and P.S. performed and analysed the X-ray spectroscopy and the neutron reflectometry. S.P., D.Z., A.J.G. and W.Z. wrote the manuscript. All authors discussed the results and implications.

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Correspondence to Weisheng Zhao.

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Supplementary Sections 1–12, Figs. 1–13 and refs. 1–8.

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Peng, S., Zhu, D., Li, W. et al. Exchange bias switching in an antiferromagnet/ferromagnet bilayer driven by spin–orbit torque. Nat Electron 3, 757–764 (2020). https://doi.org/10.1038/s41928-020-00504-6

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