Large spin-orbit torque in a-plane $\alpha$-Fe$_{2}$O$_{3}$/Pt bilayers

TL;DR

This paper demonstrates a significantly enhanced damping-like spin-orbit torque in a-plane $ ext{Fe}_2 ext{O}_3$/Pt bilayers, enabling efficient antiferromagnetic switching with potential for spintronic applications.

Contribution

It introduces a new method to quantify spin-orbit torque in antiferromagnets and shows a large DL-SOT efficiency in a-plane hematite/Pt heterostructures.

Findings

DL-SOT efficiency is two orders of magnitude larger than in other hematite orientations.

Direct imaging confirms current-induced antiferromagnetic domain motion.

A-plane $ ext{Fe}_2 ext{O}_3$/Pt is promising for efficient SOT switching.

Abstract

Realization of efficient spin-orbit torque switching of the N\'eel vector in insulating antiferromagnets is a challenge, often complicated by spurious effects. Quantifying the spin-orbit torques in antiferromagnet/heavy metal heterostructures is an important first step towards this goal. Here, we employ magneto-optic techniques to study damping-like spin-orbit torque (DL-SOT) in a-plane $\alpha$-Fe$_2$O$_3$ (hematite) with a Pt spin-orbit overlayer. We find that the DL-SOT efficiency is two orders of magnitude larger than reported in c- and r-plane hematite/Pt using harmonic Hall techniques. The large magnitude of DL-SOT is supported by direct imaging of current-induced motion of antiferromagnetic domains that happens at moderate current densities. Our study introduces a new method for quantifying spin-orbit torque in antiferromagnets with a small canted moment and identifies a-plane $\alpha$-Fe$_2$O$_3$ as a promising candidate to realize efficient SOT switching.