Field and Frequency Dependences of Mono- and Multidomain microwave Absorption in Magnetic Films

Abstract
We report both experimental and theoretical results concerning the applied dc field dependence of microwave absorption on mono and multidomain structures. Especially, we are interested in the low-field region where this absorption is due to the domain mode ferromagnetic resonance (DM-FMR) phenomenon. The sample supporting parallel stripe domains is a rare earth bismuthsubstituted single-crystal garnet film. We study the variation of DM-FMR microwave power absorption as a function of the strength of the dc field applied in the domain wall plane inside the frequency range 6-11 GHz using a highly sensitive FMR spectrometer. The power absorption spectra Pa(H) present complex shapes in the low-field region with one or two peaks. The experimental results are analyzed by adopting the formalism of Smit and Beljers. This model seems inadequate to describe precisely the whole observed behaviours and such a discrepancy will be discuss.