Studies of the ferrimagnetic resonance relaxation for hexagonal ferrites

The Kasuya-LeCraw two-magnon-one-phonon process, which is generally considered to be the primary mechanism responsible for the intrinsic ferrimagnetic resonance linewidth of perfect single crystal ferrites, is studied, taking into account the effects of the local magnetic ion symmetry on the magnon-phonon interaction coupling strength. It is shown that octahedral symmetry sites will not contribute to the coupling, but the tetrahedral and trigonal sites will. The results are used to estimate the FMR linewidth for both YIG and barium ferrite