Magnetic anisotropy in metallic ultrathin films and related experiments on cobalt films (invited)

Abstract

We present experimental and theoretical investigations on the magnetic anisotropy of Co ultrathin films sandwiched by Au. Ferromagnetic resonance experiments revealed the presence of a large perpendicular surface anisotropy that makes the easy magnetization direction become perpendicular to the film plane for Co thicknesses lower than 11 Å, as is observed in magnetization measurements. In order to explain this surface anisotropy, we propose various models, taking into account the imperfections of the films. For thicknesses below 11 Å, there is a large increase of the coercive field with decreasing thickness. This effect is tentatively interpreted in a model of propagating Bloch walls, where the interfacial roughness plays an important role.