Interaction effects in particulate recording media studied by ferromagnetic resonance

According to the Stoner-Wohlfarth theory, ferromagnetic resonance (FMR) experiments along minor loops of the hysteresis should deliver the same microwave absorption loss for vanishing applied field independent of the remanence state of a polycrystalline sample. In the present work, deviations from that prediction in particulate recording media are presented, and a strong connection of zero-field absorption and remanence magnetization of the sample, as well as the introduction of an experimental procedure to determine the interaction field with an application on differently substituted hexaferrites is shown. Additionally, the mean-field ansatz is verified to be a valid model in order to describe the influence of magnetostatic interaction in multi-particle systems. (C) 1996 American Institute of Physics.