Antiferromagnet-Mediated Spin Transfer Between Metal and Ferromagnet

TL;DR

This paper presents a theoretical model for spin transfer mediated by antiferromagnetic insulators, connecting ferromagnets and metals with strong spin-orbit coupling, and analyzes the resulting spin dynamics and voltages.

Contribution

It introduces a comprehensive theory for coherent Neel dynamics-driven spin transport through antiferromagnetic insulators coupled to ferromagnets and metals.

Findings

Spin transport is described within the adiabatic approximation.

The effect of spin current on ferromagnet resonance linewidth is evaluated.

Inverse spin Hall voltage dependence on antiferromagnet thickness is analyzed.

Abstract

We develop a theory for spin transported by coherent Neel 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 mono-domain limit and we assume its coupling to the local antiferromagnet Neel order at the ferromagnet|antiferromagnet interface through exchange coupling. Coupling between the charge current and the local Neel 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.