Concurrent magneto-optical imaging and magneto-transport readout of electrical switching of insulating antiferromagnetic thin films (B)

Abstract

Electrical writing and readout of antiferromagnetic insulators is a key prerequisite in view of using this class of materials in applications. Only recently, this has been demonstrated in insulating AFM/heavy metal bilayers by utilizing the transverse spin Hall magnetoresistance effect (SMR) as the readout. In the electrical measurement, a steplike signal resulting from a magnetic SMR contribution was reported in NiO1 and α-Fe2O32, while non-magnetic contributions due to artifacts in the heavy metal layer were found to mimic the signal expected from the magnetic switching.3,4 These results have generated a debate on the magnitude of the magnetic contributions, the reliability of the SMR readout mechanism and even on the possibility of switching domains in AFMs electrically. In our work5 we use a table-top approach to demonstrate stable and reversible current-induced switching of large-area antiferromagnetic domains in NiO/Pt by direct imaging in a Kerr microscope.6 Concurrent transport and magneto-optical imaging measurements allow us to correlate the AFM domain switching fraction and magneto-transport signal response. We establish a procedure to subtract the non-magnetic contributions and extract the magnetic SMR response from the transverse resistance signal. The disentanglement of magnetic and non-magnetic contributions clarifies the presence of a significant SMR response, associated with the switching of the antiferromagnetic domains. We thus highlight the possibility to deduce details of the antiferromagnetic switching from simple transport measurements.