Thermal Contribution to the Spin-Orbit Torque in Metallic-Ferrimagnetic Systems

Two important goals for emerging spintronic applications exploiting current-induced magnetization switching are reducing the critical current to switch the magnetization and reducing or eliminating the need for an external in-plane magnetic field for deterministic magnetization reversal. Here, we present experimental studies of the heavy-metal-ferrimagnetic bilayer system, W/CoxTb1-x characterized using magnetometry and anomalous Hall resistance measurements for temperatures ranging from 10 to 350 K. The current-induced-switching experiments are performed in the spin-orbit torque geometry where the current pulses are injected in plane and the magnetization reversal is detected by the measurement of the Hall resistance. The full magnetization reversal has been observed in all samples. Despite its large perpendicular magnetic anisotropy we find magnetic reversal for a strongly reduced in-plane magnetic field which is due to thermal contribution to switching. We find a characteristic switching temperature T-switch induced by Joule heating which is above the magnetic, T-Mcomp, and angular, T-A comp, compensation temperatures but below its Curie temperature.