Spin-Orbit Torques in Non-Collinear Antiferromagnet Mn₃Pt

Mn₃Pt is a non-collinear antiferromagnet with an fcc crystal structure and magnetic moments on the Mn atoms that are at an angle of 120° with respect to each other. This arrangement breaks the cubic symmetry and leaves only one mirror symmetry axis, which allows for the existence of the anomalous Hall effect and exotic spin-orbit torques. Here we measure the anomalous Hall effect that emerges at temperatures below 270 K, where the Mn₃Pt undergoes a magnetic transition from a collinear phase at higher temperatures to a non-collinear phase at lower temperatures. This transition is accompanied by a sudden change in resistance. Moreover, because of the symmetry breaking, we expect Mn₃Pt to generate exotic spin accumulations with an out-of-plane component at the interface with a ferromagnet. We explore the full symmetries of the spin-orbit torques by performing spin-torque ferromagnetic resonance and second harmonic Hall measurements as a function of magnetic field orientation.