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Manipulating exchange bias by spin–orbit torque

Abstract

Exchange bias, a shift in the hysteresis loop of a ferromagnet arising from interfacial exchange coupling between adjacent ferromagnetic and antiferromagnetic layers, is an integral part of spintronic devices. Here, we show that spin–orbit torque generated from spin current, a promising approach to switch the ferromagnetic magnetization of next-generation magnetic random access memory, can also be used to manipulate the exchange bias. Applying current pulses to a Pt/Co/IrMn trilayer causes concurrent switching of ferromagnetic magnetization and exchange bias, but with different underlying mechanisms. This implies that the ferromagnetic magnetization and exchange bias can be manipulated independently. Our work demonstrates that spin–orbit torque in ferromagnet/antiferromagnet heterostructures facilitates independent manipulations of distinct magnetic properties, motivating innovative designs for future spintronics devices.

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Acknowledgements

This work was partially supported by the Ministry of Science and Technology of Republic of China under Grant No. MOST 107-2218-E-007-024, MOST 106-2221-E-007-037-MY2 and MOST 106-2112-M-007-011-MY3. The authors thank Prof. Po-Tsun Liu, Prof. Ting-Chang Chang and Keithley Instruments Taiwan for the help on TRRM measurement.

Author information

P.-H.L., B,-Y,Y., M.-H.T. and K.-F.H. designed the experiments and measurements. P.-H.L., B,-Y,Y., M.-H.T. and P.-C.C. made the samples. H.-H.L. and C.-H.L. constructed the explanation of phenomenon for the exchange-bias switching by SOT; P.-H.L., B.-Y. Y., M.-H.T., H.-H.L. and C.-H.L. discussed and finished the manuscript. All authors provided the suggestions on the results and revized the manuscript.

Competing interests

The authors declare no competing interests.

Correspondence to Hsiu-Hau Lin or Chih-Huang Lai.

Supplementary information

  1. Supplementary Information

    Supplementary Figures 1–17, Supplementary Table 1, Supplementary Notes 1–12, Supplementary References 1–9

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Fig. 1: Concurrent SOT switching for FM magnetization and exchange bias.
Fig. 2: Thickness dependence of exchange bias reversal in SOT switching.
Fig. 3: Effects of current direction and longitudinal magnetic field on SOT switching in the antiparallel state (AP-mode)
Fig. 4: Independent SOT switching of FM magnetization and exchange bias.