We investigate spin-orbit torque (SOT)-induced switching in rare-earth-transition metal ferrimagnetic alloys using W/CoTb bilayers. The switching current is found to vary continuously with the alloy concentration, and no reduction in the switching current is observed at the magnetic compensation point despite a very large SOT efficiency. A model based on coupled Landau-Lifschitz-Gilbert (LLG) equations shows that the switching current density scales with the effective perpendicular anisotropy which does not exhibit strong reduction at the magnetic compensation, explaining the behavior of the switching current density. This model also suggests that conventional SOT effective field measurements do not allow one to conclude whether the spins are transferred to one sublattice or just simply to the net magnetization. The effective spin Hall angle measurement shows an enhancement of the spin Hall angle with the Tb concentration which suggests an additional SOT contribution from the rare earth Tb atoms.

We report a systematic study of current-induced perpendicular magnetization switching in W/Co x Tb 1-x /Al thin films with strong perpendicular magnetic anisotropy. Various Co x Tb 1-x ferrimagnetic alloys with different magnetic compensation temperatures are presented. The systems are characterized using MOKE, SQUID and anomalous Hall resistance at different cryostat temperature ranging from 10K to 350 K. The current-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 measuring the Hall resistance. The full reversal magnetization has been observed in all samples. Some experimental results could only be explained by the strong sample heating effect during the current pulses injection. We have found that, for a given composition x and switching polarity, the devices always reach the same temperature T switch (x) before switching independently of the cryostat temperature. T switch seems to scale with the Curie temperature of the Co x Tb 1-x ferrimagnetic alloys. This explains the evolution of the critical current (and critical current density) as a function of the alloy concentration. Future application could take advantages of this heating effect which allows reducing the in-plane external field. Unexpected double magnetization switching has been observed when the heat generated by the current allows crosses the compensation temperature.