Current-driven spin torque induced by the Rashba effect in a ferromagnetic metal layer

Abstract

Methods to manipulate the magnetization of ferromagnets by means of local electric fields1,2,3 or current-induced spin transfer torque4,5,6 allow the design of integrated spintronic devices with reduced dimensions and energy consumption compared with conventional magnetic field actuation7,8. An alternative way to induce a spin torque using an electric current has been proposed based on intrinsic spin–orbit magnetic fields9,10 and recently realized in a strained low-temperature ferromagnetic semiconductor11. Here we demonstrate that strong magnetic fields can be induced in ferromagnetic metal films lacking structure inversion symmetry through the Rashba effect. Owing to the combination of spin–orbit and exchange interactions, we show that an electric current flowing in the plane of a Co layer with asymmetric Pt and AlOx interfaces produces an effective transverse magnetic field of 1 T per 108 A cm−2. Besides its fundamental significance, the high efficiency of this process makes it a realistic candidate for room-temperature spintronic applications.

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Figure 1: Microscopic origin of the sd-mediated Rashba field and experimental geometry.
Figure 2: Differential Kerr microscopy images recorded after current pulse injection.
Figure 3: Percentage of wires that present reversed magnetic domains after the injection of a current pulse as a function of current density and external field.
Figure 4: Current density to magnetic field relationship.

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Acknowledgements

We thank A. Bachtold and S. O. Valenzuela for critically reading the manuscript and useful discussions. This work was supported by the European Research Council (Starting Grant 203239). Samples were patterned at the NANOFAB facility of the Institut Néel (CNRS).

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I.M.M., G.G., A.S. and P.G. designed the experiment; I.M.M., G.G., S.A. and B.R. fabricated the samples. I.M.M. carried out the experiments with help from S.P. and J.V.; I.M.M. and P.G. analysed the data and wrote the manuscript. All authors discussed the results and commented on the manuscript.

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Correspondence to Ioan Mihai Miron.

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The authors declare no competing financial interests.

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Mihai Miron, I., Gaudin, G., Auffret, S. et al. Current-driven spin torque induced by the Rashba effect in a ferromagnetic metal layer. Nature Mater 9, 230–234 (2010). https://doi.org/10.1038/nmat2613

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