Deterministic spin-orbit torque switching of epitaxial ferrimagnetic insulator with perpendicular magnetic anisotropy fabricated by on-axis magnetron sputtering

Current-induced switching of magnetization states in ferromagnet/spin-orbit material heterostructures has attracted significant attention, driven by the increasing need for low power consumption and a more efficient mechanism for magnetization switching. However, current shunting for the used metallic ferromagnets remains challenging in achieving low switching current densities. Thulium iron garnet, Tm3Fe5O12 (TmIG), is promising for such devices as it exhibits strong perpendicular magnetic anisotropy (PMA) and fast magnetization dynamics. However, there still remains a technological challenge in the growth of TmIG films using industry-compatible magnetron sputtering in a simple on-axis geometry for spintronic device applications. Here, we demonstrated the spin-orbit torque (SOT) magnetization switching of TmIG thin film grown by on-axis radio-frequency magnetron sputtering. Robust and deterministic SOT magnetization switching is achieved using TmIG/Pt heterostructures at a current density as low as 0.7× 10¹¹\,A/m² 0.7 × 10 11 A / m 2 . Anomalous Hall and second harmonic Hall measurements were performed to quantify effective spin-orbit fields. The effective field inducing damping-like torque is estimated to be 21±1 Oe per 107 A/cm2, higher than previous reports. These findings show a growth method for ferrimagnetic insulators with strong PMA in industry-compatible on-axis sputtering methods and its utilization for achieving energy-efficient SOT non-volatile memory applications.