Current-induced torques between ferromagnets and compensated antiferromagnets: Symmetry and phase coherence effects

Abstract

It is shown that the current-induced torques between a ferromagnetic layer and an antiferromagnetic layer with a compensated interface vanish when the ferromagnet is aligned with an axis of spin-rotation symmetry of the antiferromagnet. For properly chosen geometries, this implies that the current-induced torque can stabilize the out-of-plane (or hard-axis) orientation of the ferromagnetic layer. This current-induced torque relies on phase-coherent transport, and we calculate the robustness of this torque to phase-breaking scattering. From this, it is shown that the torque is not linearly dependent on the applied current, but has an absolute maximum.