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

We demonstrate spin Seebeck microscopy as a sensitive table-top method for imaging in-plane antiferromagnetic order in thin films. In Pt/NiO(111)/Pt samples, we resolve antiferromagnetic spin domains within crystalline twin domains and image the effects of DC current-induced spin-orbit torque switching. We find a linear correlation between spin-torque-induced changes in the integrated spin Seebeck signal and the spin Hall magnetoresistance, confirming that we image the Néel order. The measurements show that changes driven by spin-orbit torque can occur both by antiferromagnetic domain wall motion and domain flopping, and only a small fraction of the NiO sample is altered.