Magnetic anisotropies in body-centered-cubic cobalt films

Abstract

The origin of magnetic anisotropies in thin bcc cobalt films is investigated using Brillouin light scattering. The in-plane directional and wave-vector dependence of surface and bulk magnon frequencies in (110) and (001) oriented films indicate a twofold anisotropy in these cubic ferromagnets with the easy axis of magnetization lying in plane along [001] and [100], respectively. Using elastic constants determined from phonon dispersion measurements, we argue that the observed uniaxial anisotropy can be largely accounted for by magnetoelastic interactions driven by lattice mismatch at the film/substrate interface. The easy axis is also evident by the transformation of the surface spin wave into the n=0 bulk magnon when the magnon wave vector lies parallel to the spontaneous (easy) axis of magnetization.