Perpendicular switching of a single ferromagnetic layer induced by in-plane current injection

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Abstract

Modern computing technology is based on writing, storing and retrieving information encoded as magnetic bits. Although the giant magnetoresistance effect has improved the electrical read out of memory elements, magnetic writing remains the object of major research efforts1. Despite several reports of methods to reverse the polarity of nanosized magnets by means of local electric fields2,3 and currents4,5,6, the simple reversal of a high-coercivity, single-layer ferromagnet remains a challenge. Materials with large coercivity and perpendicular magnetic anisotropy represent the mainstay of data storage media, owing to their ability to retain a stable magnetization state over long periods of time and their amenability to miniaturization7. However, the same anisotropy properties that make a material attractive for storage also make it hard to write to8. Here we demonstrate switching of a perpendicularly magnetized cobalt dot driven by in-plane current injection at room temperature. Our device is composed of a thin cobalt layer with strong perpendicular anisotropy and Rashba interaction induced by asymmetric platinum and AlO x interface layers9,10. The effective switching field is orthogonal to the direction of the magnetization and to the Rashba field. The symmetry of the switching field is consistent with the spin accumulation induced by the Rashba interaction and the spin-dependent mobility observed in non-magnetic semiconductors11,12, as well as with the torque induced by the spin Hall effect in the platinum layer13,14. Our measurements indicate that the switching efficiency increases with the magnetic anisotropy of the cobalt layer and the oxidation of the aluminium layer, which is uppermost, suggesting that the Rashba interaction has a key role in the reversal mechanism. To prove the potential of in-plane current switching for spintronic applications, we construct a reprogrammable magnetic switch that can be integrated into non-volatile memory and logic architectures. This device is simple, scalable and compatible with present-day magnetic recording technology.

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Figure 1: Device schematic and current-induced switching.
Figure 2: Switching efficiency as a function of current amplitude.
Figure 3: Dependence of switching on applied field direction.
Figure 4: Prototype of a reconfigurable ferromagnetic switch.

Change history

  • 10 August 2011

    Text changes were made to the first paragraph and Fig. 4 legend.

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Acknowledgements

We thank S. O. Valenzuela and S. F. Alvarado for reading the manuscript and for discussions. This work was supported by the European Research Council (StG 203239 NOMAD), the Ministerio de Ciencia y Innovación (ERA-Net EUI2008-03884, MAT2010-15659) and the Agència de Gestió d'Ajuts Universitaris i de Recerca (2009 SGR 695). Samples were patterned at the NANOFAB facility of the Institut Néel (CNRS).

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I.M.M., K.G. and P.G. planned the experiment; I.M.M., G.G., P.-J.Z., M.V.C., S.A., S.B. and B.R. fabricated the samples; I.M.M. and K.G. performed the experiments; and I.M.M., K.G. 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 or Pietro Gambardella.

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The authors declare no competing financial interests.

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This file contains Supplementary Text and Data (see table of contents), Supplementary Figures 1-10 with legends and additional references. (PDF 1686 kb)

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Miron, I., Garello, K., Gaudin, G. et al. Perpendicular switching of a single ferromagnetic layer induced by in-plane current injection. Nature 476, 189–193 (2011). https://doi.org/10.1038/nature10309

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