Internal structure dependent creep motion of domain walls driven by spin-transfer torques

Abstract

We explore the contributions of adiabatic and nonadiabatic spin-transfer torques (STT) of a spin-polarized current to the thermally activated creep motion of domain walls in a thin (Ga,Mn)(As,P) film with perpendicular anisotropy. The nonadiabatic STT is found to compensate linearly an external magnetic field, with a slope compatible with a steady domain-wall internal structure. Close to the compensation, the adiabatic contribution is strongly enhanced and may both increase or reduce domain-wall velocity, which we associate to variations of creep pinning energy barrier with domain-wall internal structure. Far from compensation, the effects of adiabatic STT become negligible and so field and current driven domain-wall motion presents common universal behaviors described by the quenched Edwards Wilkinson universality class.