Annealing effects on FMR linewidth in Ga substituted YIG

Results of the FMR linewidth versus frequency and temperature and of the parallel pump spinwave linewidth are reported for YIG and Ga:YIG single crystal spheres subjected to different thermal treatments in O2, N2and H2/N2ambients. The slopes of the frequency dependent part of the FMR linewidth are found to be proportional to the respective measured spinwave linewidth, w hence either of these quantities represents the intrinsic FMR losses of the bulk material. The observed frequency independent park of the linewidth is assumed to represent two-magnon scattering contributions due to surface and crystal imperfections. This contribution has been further separated into two parts which depend on the anisotropy field and the saturation magnetization, respectively. The intrinsic FMR losses and the two-magnon scattering contribution are characteristically influenced by changes in the cation distribution, saturation magnetization, anisotropy field and oxygen vacancy concentration induced in the samples by the various thermal treatments.