Localized Ferromagnetic Resonance in Inhomogeneous Thin Films
Robert McMichael, A Kunz, D J. Twisselmann
The effect of sample inhomogeneity on the ferromagnetic resonance line width is determined by diagonalization of a spin wave Hamiltonian for ferromagnetic thin films with inhomogeneities. The resonance line broadening results from the distribution of the ferromagnetic resonance intensity over a large number of normal modes that span a range of eigenfrequencies. For a model inhomogeneity consisting of an applied field, dp} that varies randomly from grain to grain, the resulting line width agrees well with the two magnon model for small grains. For large grains the precession becomes localized and the spectrum approaches that the independent grains.