Asymmetric domain wall depinning under current in spin valves with perpendicular anisotropy

Abstract

We have studied the current induced domain wall depinning from an artificial constriction in Co/Ni multilayer spin valves with perpendicular magnetic anisotropy. We find that the variation in the depinning field under current is strongly dependent on the direction of propagation of the domain wall. This asymmetry arises from the stray dipolar fields generated by the reference layer, which plays an important role in influencing the magnetization reversal process under current. In particular, it can favor a nucleation process instead of domain wall motion, which may be amplified by the current.