Antiferromagnet-mediated spin transfer between a metal and a ferromagnet

Abstract

We develop a theory for spin transported by coherent N\'eel dynamics through an antiferromagnetic insulator coupled to a ferromagnetic insulator on one side and a current-carrying normal metal with strong spin-orbit coupling on the other. The ferromagnet is considered within the monodomain limit and we assume its coupling to the local antiferromagnet N\'eel order at the ferromagnet|antiferromagnet interface through exchange coupling. Coupling between the charge current and the local N\'eel order at the other interface is described using spin Hall phenomenology. Spin transport through the antiferromagnet, assumed to possess an easy-axis magnetic anisotropy, is solved within the adiabatic approximation and the effect of spin current flowing into the ferromagnet on its resonance linewidth is evaluated. Onsager reciprocity is used to evaluate the inverse spin Hall voltage generated across the metal by a dynamic ferromagnet as a function the antiferromagnet thickness.