Spin Hall magnetoresistance in antiferromagnet/heavy-metal heterostructures

TL;DR

This paper explores how spin Hall magnetoresistance in Pt/NiO heterostructures varies with magnetic field and domain structure, providing insights into antiferromagnetic spin configurations and magnetoelastic effects.

Contribution

It introduces a comprehensive model explaining magnetic field effects on spin Hall magnetoresistance in antiferromagnets, enabling estimation of magnetoelastic coupling strength.

Findings

Spin Hall magnetoresistance amplitude increases with magnetic field.

Phase shift of 90° compared to ferrimagnets.

Model estimates magnetoelastic coupling strength.

Abstract

We investigate the spin Hall magnetoresistance in thin film bilayer heterostructures of the heavy metal Pt and the antiferromagnetic insulator NiO. While rotating an external magnetic field in the easy plane of NiO, we record the longitudinal and the transverse resistivity of the Pt layer and observe an amplitude modulation consistent with the spin Hall magnetoresistance. In comparison to Pt on collinear ferrimagnets, the modulation is phase shifted by 90{\deg} and its amplitude strongly increases with the magnitude of the magnetic field. We explain the observed magnetic field-dependence of the spin Hall magnetoresistance in a comprehensive model taking into account magnetic field induced modifications of the domain structure in antiferromagnets. With this generic model we are further able to estimate the strength of the magnetoelastic coupling in antiferromagnets. Our detailed study shows that the spin Hall magnetoresistance is a versatile tool to investigate the magnetic spin structure as well as magnetoelastic effects, even in antiferromagnetic multidomain materials.