Anisotropy Dependent Spin-Orbit Torque Switching in Crystalline Ferromagnetic Semiconductor

Micromagnetic simulations using MuMax3 were employed to explore spin-orbit torque (SOT)-induced magnetization switching in single-layer crystalline ferromagnetic semiconductors (FMSs) exhibiting in-plane (IP) magnetic anisotropy. The focus was placed on the underlying mechanism for such switching. Our results demonstrate the feasibility of field-free, deterministic control of magnetization via SOT within the IP easy-axis of the FMS, contingent upon a component of carrier spin polarization aligned along this axis. This SOT-driven switching manifests as a 90° rotation between easy axes in biaxial anisotropy and a 180° rotation in uniaxial anisotropy. Simulations of field-free switching unveil the critical role of the damping-like torque (DLT) component in minimizing the current required for switching in FMS films with IP anisotropy. Conversely, investigations of SOT switching under an IP external field highlight the significance of the relative alignment between the torque exerted by the external field and the current-induced field-like torque (FLT), which hinders SOT switching process. These findings enhance our understanding of SOT switching in FMS films with diverse IP anisotropy, paving the way for developing advanced SOT-based spintronics devices.