Spin Seebeck imaging of spin-torque switching in antiferromagnetic Pt/NiO heterostructures

TL;DR

This paper introduces spin Seebeck microscopy as a novel, tabletop technique to image and study microscopic antiferromagnetic switching mechanisms in NiO/Pt heterostructures, revealing domain dynamics.

Contribution

It demonstrates the first application of spin Seebeck microscopy for imaging surface Neel order and spin domain behavior in antiferromagnetic thin films.

Findings

Resolved antiferromagnetic spin domains within twin domains.

Observed spin domain rotation and domain wall motion after spin torque.

Confirmed imaging of antiferromagnetic order via correlation with electrical measurements.

Abstract

As electrical control of N\'eel order opens the door to reliable antiferromagnetic spintronic devices, understanding the microscopic mechanisms of antiferromagnetic switching is crucial. Spatially-resolved studies are necessary to distinguish multiple nonuniform switching mechanisms; however, progress has been hindered by the lack of tabletop techniques to image the N\'eel order. We demonstrate spin Seebeck microscopy as a sensitive, table-top method for imaging antiferromagnetic order in thin films, and apply this technique to study spin-torque switching in NiO/Pt and Pt/NiO/Pt heterostructures. We establish the interfacial antiferromagnetic spin Seebeck effect in NiO as a probe of surface N\'eel order, resolving antiferromagnetic spin domains within crystalline twin domains. By imaging before and after applying current-induced spin torque, we resolve spin domain rotation and domain wall motion, acting simultaneously. We correlate the changes in spin Seebeck images with electrical measurements of the average N\'eel orientation through the spin Hall magnetoresistance, confirming that we image antiferromagnetic order.