Magnetic anisotropies of Fe/sub n//V/sub m/[001] superlattices determined by ferromagnetic resonance

The temperature-dependent magnetic anisotropies of Fe
_n
/V
_m
(001) superlattices on MgO(OO1) were determined by Ferromagnetic Resonance (FMR). The Fe-layer thickness n ranges between 2 and 4 atomic layers. The shape anisotropy dominates, and the easy-axis of the magnetization of the samples is always in the film plane. The second-order out-of-plane magnetic anisotropy is mainly determined by magnetoelastic effects due to the in-plane lattice expansion of the Fe. The fourth order in-plane anisotropy presents a strong temperature dependence as a result of the competition between a volume part favoring the Fe-[100] and a surface part favoring the Fe[ll0] in-plane direction. A very small stepinduced in-plane uniaxial anisotropy reveals the existence of very-large atomically-flat terraces. This information, in combination with the observation of very narrow FMR-linewidths, indicates the excellent structural quality of our samples.