Sincrotró ALBA
Prof. Yoshishige Suzuki - Osaka University, Japan
Quan
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Ana De La Osa
We have 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). 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, our 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. 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. The main reason of this difficulty is because of insufficient control of interfaces in our samples, although the effect is very sensitive to it.
In my talk, I will also address to those difficulties and mention to a recent progresses in understanding the mechanism through x-ray absorption spectroscopy and XMCD measurements.