Spin-Orbit-Torque Efficiency in Compensated Ferrimagnetic Cobalt-Terbium Alloys

To reach the subnanosecond switching speeds desired for spintronic applications, antiferromagnetically coupled materials seem ideal. In this study, current-induced switching is shown to be most efficient in transition-metal---rare-earth alloys, where torques work constructively on two antiparallel sublattices of spins. There is also evidence for conservation of total angular momentum for spin-orbit-torque switching---experimental proof that the ``bookkeeping picture'' of the spin torque still holds in these ferrimagnetic systems.