講演情報
[23p-A201-4]Self-induced spin-orbit torque in metallic bi-layer systems
〇Motomi Aoki1,2, Ei Shigematsu1, Ryo Ohshima1,2, Teruya Shinjo1,2, Masashi Shiraishi1,2, Yuichiro Ando1,2,3 (1.Kyoto Univ., 2.CSRN Kyoto Univ., 3.PRESTO, JST)
キーワード：
Spin Hall effect、Spin orbit torque
In a nonmagnet (NM)/ferromagnet (FM) bilayer structure, electric current in the NM layer generates spin current via charge-to-spin conversion such as the spin Hall effect (SHE), resulting in a spin-current injection into the FM layer. Injected spin current exerts torque on the magnetization of the FM layer, which is called spin-orbit torque (SOT). Whereas most of SOT experiments have focused on the SHE in NMs, spin-current outflow from the FM to NM layer also exerts torque on the magnetization of the FM itself. Therefore, we must consider the SHE in the FM layer when analyzing the SOT in the NM/FM bilayer systems.
In our research, we observed anomalous sign inversion of the SOT in Ta/Co bilayer structure as increasing the thickness of Co layer, which originates from the competition between SOT via the SHE in Ta and the self-induced SOT (SI-SOT) via the SHE in Co. We estimated contribution of the SI-SOT to be -43 % and 27 % of the measured SOT for Ta/Co and permalloy/Pt, respectively. Moreover, our calculation indicates that the influence of the SI-SOT becomes significant when the resistivity of the NM layer is high.
In our research, we observed anomalous sign inversion of the SOT in Ta/Co bilayer structure as increasing the thickness of Co layer, which originates from the competition between SOT via the SHE in Ta and the self-induced SOT (SI-SOT) via the SHE in Co. We estimated contribution of the SI-SOT to be -43 % and 27 % of the measured SOT for Ta/Co and permalloy/Pt, respectively. Moreover, our calculation indicates that the influence of the SI-SOT becomes significant when the resistivity of the NM layer is high.