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

Abstract

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, Tm<inf>3</inf>Fe<inf>5</inf>O<inf>12</inf> (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 0.7×1011A/m2. 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 107A/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. © 2025 Elsevier B.V., All rights reserved.