Domains and magnetization reversal dynamics in Au/Co/Au (1 1 1) ultrathin films: Co and Au thickness dependence

The magnetic anisotropy of epitaxial ultrathin Co-films on Au(111) depends drastically on Co- or Au-overlayer thickness. We have used polar magneto-optical Kerr effect on stepped-wedge samples to perform ex situ domain imaging, together with in situ and ex situ magnetic aftereffect measurements. Domains configurations and magnetization reversal dynamics were thus investigated versus perpendicular magnetic anisotropy strength. Large changes with Co thickness in Au/Co/Au(111) sandwiches are observed; they can be interpreted using existing theories. The drastic evolution of the dynamics of the magnetization reversal process with submonolayer Au coverage is attributed to a structural reorganization of the Co-layer with Au deposition, due to surfactant effect.