Direct imaging of current-induced antiferromagnetic switching revealing a pure thermomagnetoelastic switching mechanism

TL;DR

This study uses imaging and simulations to reveal that current-induced switching in antiferromagnetic NiO/Pt devices is driven by thermomagnetoelastic effects, not spin-orbit torque, highlighting a heat-dependent strain mechanism.

Contribution

It demonstrates a pure thermomagnetoelastic switching mechanism in antiferromagnetic systems, challenging previous spin-orbit torque explanations and providing new insights into magnetic control.

Findings

Switching states depend on device geometry and current direction.

Heat-induced strain is the key driver of magnetic domain switching.

The mechanism explains previously conflicting experimental results.

Abstract

We unravel the origin of current-induced magnetic switching of insulating antiferromagnet/heavy metal systems. We utilize concurrent transport and magneto-optical measurements to image the switching of antiferromagnetic domains in specially engineered devices of NiO/Pt bilayers. Different electrical pulsing and device geometries reveal different final states of the switching with respect to the current direction. We can explain these through simulations of the temperature induced strain and we identify the thermomagnetoelastic switching mechanism combined with thermal excitations as the origin, in which the final state is defined by the strain distributions and heat is required to switch the antiferromagnetic domains. We show that such a potentially very versatile non-contact mechanism can explain the previously reported contradicting observations of the switching final state, which were attributed to spin-orbit torque mechanisms.