Intrinsic relaxation of the ferromagnetic resonance in substituted yttrium iron garnets

The intrinsic loss properties of the ferromagnetic resonance (FHR) in Ga, Al, Sc and V substituted iron garnets have been investigated at different temperatures from T=77 K up to the Curie temperature by FHR measurements as a function of frequency. After separation of masking two-magnon scattering contributions the intrinsic losses of the bulk single crystal materials were resolved in terms of the dimensionless Landau-Lifshitz damping parameter αf. The results of αf(T) obtained for different temperatures were found to increase linearly versus1/4\piM_{s}(T), the reciprocal of the respective saturation magnetization. Apart from the region of magnetic compensation the intrinsic FHR losses for 100 K chave been related directly to thermomagnetic properties of substituted YIG using nearly invariant matching parameters.