Temperature dependence of spin-orbit torques across the magnetic compensation point in a ferrimagnetic TbCo alloy film

The temperature dependence of spin-orbit torques (SOTs) and spin-dependent transport parameters is measured in bilayer Ta/TbCo ferrimagnetic alloy films with bulk perpendicular magnetic anisotropy. We find that the dampinglike (DL)-SOT effective field diverges as temperature is swept through the magnetic compensation temperature (T-M), where the net magnetization vanishes due to the opposing contributions from the Tb and Co sublattices. We show that DL-SOT scales with the inverse of the saturation magnetization (M-s), whereas the spin-torque efficiency is independent of the temperature-dependent Ms. Our findings provide insight into spin transport mechanisms in ferrimagnets and highlight low-M-s rare-earth/transition-metal alloys as promising candidates for SOT device applications.