Spin-Transfer-Torque Driven Domain Wall Motion in (Ga,Mn)(As,P)

Precise control of domain wall (DW) motion in magnetic materials is a prerequisite for the realization of novel non-volatile and down-scalable logic/memory devices which promise to overcome the limitations of current technologies. While magnetic fields are the obvious choice for DW manipulation, in spin-orbit (SO) coupled materials, electric fields provide an additional means of control via current-induced spin torque. We extend the existing theoretical framework used to describe magnetization dynamics in uniform ferromagnets (FM) to dilute FM semiconductors. Analogous to the study of homogeneous systems, we compute the current-induced internal fields (CIF) corresponding to the spin torques and perform a quantitative analysis of the effect of CIFs on DW motion by solving the phenomenological Landau-Lifshitz-Gilbert equations. Microscopic calculations based on an accurate description of the SO coupling effects are used to estimate the observed anisotropies. Our theoretical efforts are complemented by experimental studies in the SO coupled FM (Ga,Mn)(As,P).