Anisotropy dependent spin-orbit torque switching in crystalline ferromagnetic semiconductor

Micromagnetic simulations using MuMax 3 were employed to explore spin-orbit torque (SOT)-induced magnetization switching in single-layer crystalline ferromagnetic semiconductors (FMS) exhibiting in-plane 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 in-plane 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 in-plane anisotropy. Conversely, investigations of SOT switching under an in-plane 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 in-plane anisotropy, paving the way for developing advanced SOT-based spintronics devices.