講演情報
[8p-E208-8]Enhancement of current-induced torque in Cr/CoFeB/MgO by varying sputtering conditions
〇Yukihiro Marui1, Ryosuke Yamamoto1,2, Shunya Chiba1, Shunsuke Fukami1,2,3,4,5,6 (1.RIEC, Tohoku Univ., 2.Dept. Electron. Eng., Tohoku Univ., 3.WPI-AIMR, Tohoku Univ., 4.CSIS, Tohoku Univ., 5.CIES, Tohoku Univ., 6.InaRIS)
キーワード：
Orbitronics、Spin-Obitironics、Orbital torque
Spin-orbit torque (SOT) and orbital torque (OT) provide efficient routes for current-induced magnetization control in nonmagnetic material/ferromagnet bilayers. While SOT originates from charge-to-spin current conversion, OT has recently attracted attention as its orbital counterpart. However, the microscopic origin of OT and the factors governing its magnitude remain unclear. In this study, we investigate how sputtering conditions affect the resistivity of Cr and the resulting current-induced torque in Cr/CoFeB bilayers. Cr/CoFeB films were fabricated on thermally oxidized Si substrates by DC/RF magnetron sputtering, and the effective spin-orbital Hall conductivity was evaluated using harmonic Hall measurements. The layer thicknesses were selected based on our previous study, where OT was found to dominate. We find that lower Ar sputtering pressure reduces the Cr resistivity and significantly enhances the effective spin-orbital Hall conductivity. This behavior differs from conventional SOT trends, suggesting a distinct mechanism for OT. These results offer new insight into orbital transport and torque generation in Cr-based systems.