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Large voltage-induced magnetic anisotropy change in a few atomic layers of iron

Abstract

In the field of spintronics, researchers have manipulated magnetization using spin-polarized currents1,2,3. Another option is to use a voltage-induced symmetry change in a ferromagnetic material to cause changes in magnetization or in magnetic anisotropy4,5,6,7,8,9,10,11,12,13,14. However, a significant improvement in efficiency is needed before this approach can be used in memory devices with ultralow power consumption. Here, we show that a relatively small electric field (less than 100 mV nm−1) can cause a large change (40%) in the magnetic anisotropy of a bcc Fe(001)/MgO(001) junction. The effect is tentatively attributed to the change in the relative occupation of 3d orbitals of Fe atoms adjacent to the MgO barrier. Simulations confirm that voltage-controlled magnetization switching in magnetic tunnel junctions is possible using the anisotropy change demonstrated here, which could be of use in the development of low-power logic devices and non-volatile memory cells.

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Figure 1: Schematic of the sample used for a voltage-induced magnetic anisotropy change.
Figure 2: Magneto-optical Kerr ellipticity ηk for different applied voltages as a function of applied field.
Figure 3: Fe layer thickness dependencies of the voltage modulation response of ηK, saturation Kerr ellipticity ηs, and Eperpd.
Figure 4: A macro spin model simulation of voltage-controlled magnetization switching.

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Acknowledgements

The authors would like to thank D. Yamaguchi, Y. Sobajima, T. Toyama and H. Okamoto for their assistance in ITO deposition. The authors also acknowledge H. Kubota, W. Van Roy, S. Blügel and T. Miyazaki for their valuable comments. A part of the research was conducted under the financial support of Grant-in-Aid for Scientific Research (A19206002) and G-COE program of Ministry of Education, Culture, Sports, Science and Technology-Japan (MEXT).

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Y.S. conceived and designed the experiments and performed micro magnetic calculation. T.M. and Y.S. performed the experiments and analysis. T.N. and A.A.T. led experiments and physical discussions. K.O., N.T. and M.M. established experimental techniques. S.M. and Y.A. performed FMR measurements. M.S. and T.S. contributed to general discussions. T.M. wrote the paper with review and input from Y.S., T.N. and A.A.T.

Corresponding author

Correspondence to Y. Suzuki.

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Maruyama, T., Shiota, Y., Nozaki, T. et al. Large voltage-induced magnetic anisotropy change in a few atomic layers of iron. Nature Nanotech 4, 158–161 (2009). https://doi.org/10.1038/nnano.2008.406

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