Micromagnetic simulations for magnetic-field-free magnetization switching by spin-orbit torque in a perpendicularly magnetized (Ga,Mn)As single layer

Spin-orbit torque (SOT) provides an efficient electrical means of magnetization switching in magnetic materials, presenting a significant potential for advancing next-generation information storage and memory technologies. In this study, we successfully demonstrate highly efficient SOT magnetization switching in a perpendicularly magnetized (Ga,Mn)As single layer, achieved without the assistance of an external magnetic field. To further investigate the underlying physical mechanisms, we employed micromagnetic simulations incorporating the Dzyaloshinskii-Moriya interaction, known for breaking the in-plane symmetry in SOT magnetization switching. Our findings indicate that the Dzyaloshinskii-Moriya interaction (DMI) plays a crucial role in enabling field-free spin-orbit torque (SOT) magnetization switching in the (Ga,Mn)As layer. Furthermore, we found that the direction of the DM effective field is determined by the initial magnetization states, leading to varying polarities of SOT magnetization switching. This work deepens our understanding of field-free magnetization switching mechanisms and paves the way for developing highly efficient SOT-based devices.