Ferromagnetic resonance of epitaxial Fe81Ga19(110) thin films

Using ferromagnetic resonance techniques, we have characterized a set of Fe₈₁Ga₁₉ (110) thin films epitaxially grown on Si (100) with a Cu (100) buffer layer. We have observed that the symmetry of the in-plane angular variation of the resonance field and the linewidth are dependent on the film thickness. The angular variation of the resonance field of thinner films (thickness ≤ 40 nm) can be well fitted assuming the presence of two perpendicular growth modes or variants with cubic anisotropy. Results in thicker films are best explained by two non perpendicular variants. An inplane field-induced uniaxial anisotropy is also needed to explain the observed spectra. The cubic anisotropy tends to increase with film thickness with values in the range K₁ = 0.8 × 10⁵-3.6 × 10 ⁵ erg/cm³. The angular variation of the linewidth can be explained assuming a dispersion in the values of the cubic anisotropy fields.