Magnetization Processes in Ultrathin Co Film Grown on Stepped Si(111) Substrate

The aim of the paper is to study the magnetization processes and magnetic domain structure in epitaxial ultrathin Co films grown on stepped Si(111) substrates. The surfaces after Cu and Au/Cu coverage were investigated using in situ STM technique. The thickness driven evolution of hysteresis loops corresponds to spin-reorientation transition above 7 monolayers (ML) Co thickness. The in-plane magnetic anisotropy symmetry was deduced from magneto-optical (MOKE) hysteresis loops. The experimental data are discussed taking into account contributions of both perpendicular and in-plane uniaxial step-induced anisotropy. The preference of domain wall propagation for 3 and 5 ML Co thicknesses could be explained by the step-induced in-plane magnetic anisotropy determined from in-plane MOKE measurement.