Spin-Orbit Torque in Structures With Magnetization-Compensated MnGa/Co2MnSi Bilayer

We have systematically investigated the spin-orbit torque (SOT)-induced effective magnetic field in a structure consisting of a Ta heavy metal layer and an antiferromagnetically coupled Mn_1.8Ga₁/Co₂MnSi (CMS) bilayer around the magnetization compensation point by varying CMS film thickness. The efficiency of SOT generation takes the maximum around the compensation point, and it is approximately six times as large compared with that in the devices with a MnGa single structure. The enhancement of SOT efficiency can be explained mainly by the reduction in saturation magnetic moment around the compensation point. Moreover, a significant enhancement of the effective spin Hall angle was observed around the compensation point because of the inversion of the magnetization configuration before and after the compensation point.