Efficiency of Spin-Transfer Torque-Assisted Spin-Orbit Torque Magnetization Switching Under In-Plane External Field Application

We have simulated the magnetization dynamics under implementing spin-transfer torque (STT) and spin-orbit torque (SOT) simultaneously, which is regarded as the writing process of the next-generation 3-D domain wall magnetic memory (3D-DWMM). In previous research, we fabricated a GMR device and studied the STT-assist SOT switching experimentally and discovered that the STT-assist efficiency was dependent on external field. In this study, we analyzed how external field affects the STT-assisted SOT switching as well as the STT-assist efficiency. The experimental STT-assisted SOT switching was successfully reproduced by the simulation, and it was found that the increase of SOT torque will reduce both the switching current density and STT-assist efficiency. The results suggest that the balance between STT and SOT torques will be important to obtain small switching current density as well as large assist efficiency for field-free SOT switching of 3D-DWMM.