Characterization of Spin-Orbit Torque in a Single Ferrimagnetic Gdfeco Film by Oblique Sputtering

We report oblique angle-modulated spin-orbit torque (SOT) in a single ferrimagnetic GdFeCo alloys based on spin-torque ferromagnetic resonance (ST FMR). Thickness-dependent anomalous Hall measurements reveal bulk perpendicular magnetic anisotropy of the film. ST FMR is performed to quantify SOT; the spectras show a single reasonance peak for thin film corresponding to the in-plane magnetization precession modes, another peak appears for thicker film corresponding to the out-of-plane precession modes. The full angular-dependence of the ST FMR spectra reveals that SOT decreases with increasing oblique sputtering angle. This finding provides an alternative way to modulate SOT in ferrimagneitc spintronic devices.