Abstract
The magnetization direction of a metallic magnet has generally been controlled by a magnetic field or by spin-current injection into nanosized magnetic cells1,2. Both these methods use an electric current to control the magnetization direction; therefore, they are energy consuming. Magnetization control using an electric field3 is considered desirable because of its expected ultra-low power consumption and coherent behaviour. Previous experimental approaches towards achieving voltage control of magnetization switching have used single ferromagnetic layers with and without piezoelectric materials, ferromagnetic semiconductors, multiferroic materials, and their hybrid systems4,5,6,7,8,9,10,11,12,13,14,15. However, the coherent control of magnetization using voltage signals has not thus far been realized. Also, bistable magnetization switching (which is essential in information storage) possesses intrinsic difficulties because an electric field does not break time-reversal symmetry. Here, we demonstrate a coherent precessional magnetization switching using electric field pulses in nanoscale magnetic cells with a few atomic FeCo (001) epitaxial layers adjacent to a MgO barrier. Furthermore, we demonstrate the realization of bistable toggle switching using the coherent precessions. The estimated power consumption for single switching in the ideal equivalent switching circuit can be of the order of 104kBT, suggesting a reduction factor of 1/500 when compared with that of the spin-current-injection switching process.
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Acknowledgements
We would like to thank H. Tomita for his help with the simulations as well as S. Miwa for useful discussions. Y. Shiota thanks the Japan Society for the Promotion of Science for the fellowship. Part of this research was conducted under the financial support of the Global Center of Excellence (G-COE) program of the Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT).
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Y. Suzuki conceived and designed the experiments. Y. Shiota performed the experiments, simulations, and analysis. T.N. and Y. Suzuki led experiments and physical discussions. F.B., S.M., and T.S. contributed to the general discussions. Y. Shiota wrote the paper with reviews and inputs from Y. Suzuki and T.N.
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Shiota, Y., Nozaki, T., Bonell, F. et al. Induction of coherent magnetization switching in a few atomic layers of FeCo using voltage pulses. Nature Mater 11, 39–43 (2012). https://doi.org/10.1038/nmat3172
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DOI: https://doi.org/10.1038/nmat3172
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