Bias Magnetic Field Dependence of RF Permeability in Thin Permalloy Films

Dependence of RF permeability (¿RF = ¿´RF - j ¿´´RF) on a bias magnetic field (H: corresponding to a signal field) in a permalloy film, when H and RF exciting magnetic fields (HRF) are in the direction of the hard axis in Permalloy films, was analyzed with the film taken as a single domain, the demagnetizing field in the film plane taken as 0, HRF assumed to be sufficiently small compared with the anisotropic field HK, and H assumed to be static. It was found that the ¿´RF change is sharp at ¿ ≪ ¿K (¿ß: ferromagnetic resonance frequency at H = 0) and the ¿´´RF change is sharp at ¿ ¿ ¿K.