Spin dynamics and magnetic anisotropies at the Fe/GaAs(001) interface

20Au/(d)Fe/GaAs(001) structures were deposited using molecular beam epitaxy, where Fe thickness d = (5...90) atomic layers. Interface anisotropies were investigated using the in-plane angular dependence of ferromagnetic resonance (FMR). Intrinsic and extrinsic contributions to magnetic damping were investigated using FMR linewidth (ΔH) measurements at 9, 24, 36, and 72 GHz (in-plane configuration) and 9, 24, and 36 GHz (perpendicular configuration). The in-plane cubic and uniaxial perpendicular anisotropies were well described by the bulk and interface contributions indicating that the Fe films have a high lattice coherence and high critical Curie temperature Tc. The in-plane uniaxial anisotropy is more complex and will be discussed in detail. The frequency dependence of ΔH(f) was analyzed using the Gilbert damping, two magnon scattering, and long range magnetic inhomogeneity contributions. The thickness dependence of the Gilbert damping parameter α was found to be well described by the bulk and interface terms.