Microwave Resonance in Hexagonal Ferrimagnetic Single Crystals

The resonance conditions for a hexagonal single crystal with hard direction normal to the basal plane, and magnetocrystalline anisotropy with hexagonal symmetry in the basal plane, are presented. The anisotropy energy surface may be described by E=K0+K1α32+K2α34+K3α36+K4(α16−15α14α22+15α12α24−α26). From the resonance conditions and data on a single crystal of Ba2Co2Fe12O22 we find K1 = 1.38×105 ergs/cm3, K2+3/2K3=1.42×106 ergs/cm3, and K4=1.10×104. These constants with the loss parameter determined from measurements of the ferromagnetic resonance line width accurately predict the initial permeability spin resonance in a partially oriented polycrystalline sample.