Effect of demagnetizaing field on frequency dispersoin of complex permeability

This paper describes that the ferromagnetic resonance (FMR) frequency shift can be calculated by an electromagnetic field simulator based on the Maxwell's equation although the relative permeability and the FMR frequency is defined by the Landau-Lifshitz-Gilbert (LLG) and the Kittel's equation. We evaluate the magnetic circuit model with the leakage magnetic flux path for considering the demagnetizing field generated in the magnetic film. As the result, we clarify that the effect of the demagnetizing field is considered as a reluctance of the leakage magnetic flux path in the magnetic circuit calculation, which is considered as the increase of anisotropy field in the Kittel's equation. Furthermore, we show that the simulated FMR frequency by the electromagnetic simulator agrees with the measured values.