The exchange stiffness (Aex) is one of the key parameters controlling magnetization reversal in magnetic materials. We used a method based on the spin spiral formation in two ferromagnetic films antiferromagnetically coupled across a non-magnetic spacer layer and Brillouin scattering to measure Aex for a series of Co1-δXδ (X = Cr, Ni, Ru, Pd, Pt) thin film alloys. The results show that Aex of Co alloys does not necessarily scale with Ms; Aex approximately decreases at the rate of 1.1%, 1.5%, 2.1%, 3.5%, and 5.6%, while Ms decreases at the rate of 1.1%, 0.5%, 1.1%, 3.7%, and 2.5% per addition of 1 at % of Pt, Ni, Pd, Cr, and Ru, respectively.
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.
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