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 s ame microwave absorption loss for vanishing applied field independent of the remanence state of a polycrystalline sample. In the present wor k, deviations from that prediction in particulate recording media are presented, and a strong connection of zero-field absorption and remane nce magnetization of the sample, as well as the introduction of an exp erimental procedure to determine the interaction field with an applica tion on differently substituted hexaferrites is shown. Additionally, t he mean-field ansatz is verified to be a valid model in order to descr ibe the influence of magnetostatic interaction in multi-particle syste ms. (C) 1996 American Institute of Physics.