Calculation of FMR in interacting fine particle systems

A computer model has been developed to simulate ferromagnetic resonance (FMR) in a randomly packed interacting fine particle system. Using Stoner-Wohlfarth particles with a random distribution of easy axes, the FMR response was calculated from the second derivatives of the equilibrium energy. The results show a qualitative agreement with available experimental data and are in agreement with previous mean field calculations. However, it is shown that the mean field theory does not predict changes in the interaction effects as the field is reduced from saturation.