17:30 〜 17:45
▲ [24p-E202-14] Voltage induced coercivity change in Pt/Co/amorphous TiOx structure
キーワード：VCMA effect, dielectric constant, surface oxidation
Voltage controlled magnetic anisotropy (VCMA) effect has been attracted much attentions as a low-power-consumption spin manipulation technique. Fcc-Co (111)-based systems is a promising candidate, on account of its large PMA. However, the absence of a suitable dielectric layer material linked to the limited VCMA researches. In this study, we focused on a high-k amorphous TiOx as a dielectric layer material and investigated the voltage induced coercivity (Hc) change in nominally Pt/Co/TiOx structures[1].
The amorphous TiOx layer was prepared using an oxygen radical-assisted MBE technique at room temperature. We found a surface oxidation of Co, thus formation of CoO, occurs during the TiOx deposition. We evaluated the dielectric constant of CoO/TiOx bilayer to be ~29. We investigated the Co thickness dependence of the voltage induced Hc change by MOKE and found that a large Hc change was obtained for a relative thick Co sample (nominally 1.7 nm, Fig. 1). The obtained voltage induced Hc change (~20 mT by the application of 2 V, or 0.32 V/nm) is about one orders of magnitude larger than those reported for Pt/Co/oxide systems. The large voltage induced Hc change may be the results of the surface oxidation of Co[2], the large dielectric constant (~29), and the relative thick Co thickness.
References : [1] T. Nozaki et al., Sci. Rep. 11, 21448 (2021). [2] J. Shiogai et al., J. Phys. D: Appl. Phys. 49, 03LT01 (2016).
The amorphous TiOx layer was prepared using an oxygen radical-assisted MBE technique at room temperature. We found a surface oxidation of Co, thus formation of CoO, occurs during the TiOx deposition. We evaluated the dielectric constant of CoO/TiOx bilayer to be ~29. We investigated the Co thickness dependence of the voltage induced Hc change by MOKE and found that a large Hc change was obtained for a relative thick Co sample (nominally 1.7 nm, Fig. 1). The obtained voltage induced Hc change (~20 mT by the application of 2 V, or 0.32 V/nm) is about one orders of magnitude larger than those reported for Pt/Co/oxide systems. The large voltage induced Hc change may be the results of the surface oxidation of Co[2], the large dielectric constant (~29), and the relative thick Co thickness.
References : [1] T. Nozaki et al., Sci. Rep. 11, 21448 (2021). [2] J. Shiogai et al., J. Phys. D: Appl. Phys. 49, 03LT01 (2016).