High electrical and optical resistive switching in a thin-film antiferromagnet.

Ferromagnets and antiferromagnets represent two fundamental forms of magnetism with antiferromagnets being the more abundant of the two but notoriously hard to explore and exploit. Recent demonstrations of electrical detection and switching of the antiferromagnetic order vector have opened a prospect of ultra-fast memories robust against charge and magnetic-field perturbations and prompted systematic research into the rich symmetry and topology landscape of antiferromagnets. The previously considered reorientation of the antiferromagnetic order by a spin-orbit torque however, results in readout signals of impractically low values and has not allowed for complementing electrical switching with optical control. Here we present our observation of large resistive switching ratios approaching 100%. Unlike the ferromagnetic giant magnetoresistance, we achieve his in an antiferromagnet without introducing a complex multi-layer structure. We use elementary resistor devices made of a single-layer film of CuMnAs and demonstrate, side by side, electrical and optical switching which we scale down to a single 100 fs laser pulse. By realizing detection via optical reflectivity we complete the tool-box of electrical and optical writing and readout. We illustrate the utility of this unanticipated switching principle of antiferromagnets for the development of analog neuromorphic devices. We discuss the origin of our switching signals based on the results of magnetic microscopy studies.