Effects of atomic-scale Cu structures on the magnetic anisotropy and magneto-optical response of ultrathin Co films

We present magneto-optical Kerr effect measurements of epitaxial Co/Cu(001) films studied in situ as submonolayer quantities of Cu are deposited under ultrahigh-vacuum conditions. An enhancement of the magneto-optical response coincides with changes in the remanence behaviour, which are shown to be due to a variation in the ratio of the uniaxial and cubic inplane magnetic anisotropy strengths. The data are consistent with the preferential growth of Cu atoms at atomic steps due to the substrate: these Cu 'wires' reduce the step-induced uniaxial anisotropy and their electronic structure strongly affects the magneto-optical response.