Enhanced Spin-Orbit Torque and Multilevel Current-Induced Switching in W/Co−Tb/Pt Heterostructure

In spintronics, ferrimagnets continue to draw intense attention for their ultrafast dynamics, but their reduced magnetization near the compensation point plus small spin-mixing conductance do not help the spin-orbit torque in ferrimagnet/heavy-metal multilayers. This study uses two heavy metals with opposite spin Hall angles flanking a typical ferrimagnetic alloy to achieve effective enhancement of the spin Hall angle, as well as stable, controllable multilevel current-induced switching based on the proposed heterostructure. This work, combining efficient and multibit magnetization switching, provides an alternate route to leveraging ferrimagnets in spintronic devices.