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Thursday, 09 July 2015

Prof Yoshishige Suzuki offers an ICN2 Seminar about Electric field effects on metallic ferromagnetic thin layers

Prof Yoshishige Suzuki, from the Osaka University (Japan), visited ICN2 after taking part in the International Conference on Magnetism celebrated in Barcelona. Dr. Frédéric Bonell, Postdoctoral Researcher at the Physics and Engineering of Nanodevices Group, worked with him before arriving ICN2 and presented the Seminar.

Prof Yoshishige Suzuki, from the Osaka University (Japan) offered on July 8 an ICN2 Seminar entitled “Electric field effects on metallic ferromagnetic thin layers and its applications”. He reported how his Group has recently started a national research program "ImPACT", which aims to develop energy saving IT solutions. In the program, our group leads a project to investigate voltage driven magnetic random-access memories (MRAMs). Dr. Frédéric Bonell, Postdoctoral Researcher at the Physics and Engineering of Nanodevices Group, worked with him before arriving ICN2 and presented the Seminar.

Since a magnetization control using an electric field at room temperature will be useful because of its expected ultra-low power consumption, the project tries to make clear the possibility of "voltage torque MRAM" by a collaboration between many research groups from University, national institutes and companies. In the talk, Prof. Yoshishige explained the targets and challenges of the project will be explained.

Magnetic anisotropy control using electric field at room temperature in all solid-state devices was first done using an Fe ultrathin film grown on Au(001) surface and covered by an MgO layer [2]. The effect was soon applied to switch magnetization coherently, to excite ferromagnetic resonance, and to modulate spin waves. The modulation of spinwaves also revealed a control of Dzyaloshinskii-Moriya interaction by an applied electric field. However, theoretical understanding of the effect has not been satisfactory.

The size of the effect are in rough agreement with theories, however, even the sign of the effect can be opposite. According to Prof. Yoshishige, the main reason of this difficulty is because of insufficient control of interfaces in our samples, although the effect is very sensitive to it. During his talk, Prof. Yoshishige also addressed those difficulties and mentioned recent progresses in understanding the mechanism through x-ray absorption spectroscopy and XMCD measurements.