Normal mode mixing and ferromagnetic resonance linewidth

Summary form only given. A recent work by McMichael et. al. described a repulsion between interacting ferromagnetic resonance (FMR) modes when only two such modes are strongly coupled with the two magnon model. Mode repulsion is consistent with diagonalizing a two mode system but it is not a realistic model for most physical systems. The two magnon model is an application of perturbation theory used to describe scattering from in FMR between k=0, the uniform precession mode, to other k/spl ne/0 spin wave modes. In this work we take a different approach valid for large perturbations by diagonalizing the full Hamiltonian including interactions between all spin wave modes, as well as looking at other modes than just the uniform precession mode.