Domain-Wall Dynamics In A Nanostrip With Perpendicular Magnetic Anisotropy Induced By Perpendicular Current Injection

A numerical and analytical study of the dynamics of domain walls (DWs) in a magnetic tunnel junction with perpendicular magnetic anisotropy in a free layer is presented. Equilibrium states of the domain wall are obtained for various widths of the structure. The corresponding symmetries of the components of spin transfer torques T-STT and the polarizer directions favoring stable DW motion under perpendicular current injection are obtained. The DW steady motion with velocities up to 200 m/s at current densities below 10(6) A/cm(2) is reported. The Walker breakdown is demonstrated, and the dynamics of the postthreshold DW motion is investigated for various configurations of torques and polarizer directions. To have analytical insight into the investigated regimes of DW dynamics a theoretical model is developed and verified by micromagnetic simulations.