Modeling SOT-Driven Domain Wall Motion in MTJ Switching

Spin orbit torque (SOT)-based magnetic tunneling junction (MTJ) switching is central to magnetic random-access memories (MRAMs) where additional physical effects such as domain wall (DW) motion often coexist. This work provides an analytical framework for Dzyaloshinski-Moriya-Interaction (DMI)-induced DW propagation in confined MTJ structures using the Euler-Lagrange variational approach. We highlight the key implication of varying DW length in confined MTJs and propose a pseudo-steady-state solution for estimating the DW velocity. Our model is verified by micromagnetic simulations across a wide range of parameter space and thus sets up a solid foundation towards circuit-compatible SOT-MRAM compact models.