Thermally activated domain wall motion in [Co/Ni](111) superlattices with perpendicular magnetic anisotropy

This article presents field-induced magnetization dynamics in a [Co/Ni] superlattice exhibiting strong perpendicular magnetic anisotropy using Kerr microscopy. Domain wall velocity is reported within thermally activated, transitory and flow dynamical regimes. At low field, the thermally activated regime is characterized by dendritic domain growth that differs from the creep mechanism usually observed for the interaction of domains wall with a 2D random pinning potential for layers grown by sputtering. This result is explained by the epitaxial nature of the [Co/Ni] superlattices involving a single-type defect. The transition from the thermally activated to the flow regime is characterized by a reduction of the density of non-reversed domains which exist after domain wall displacement. The effect of spin transfer torque on domain wall is also discussed.