Fine structure of ferromagnetic-resonance spectra of disperse magnets

The technique of ferromagnetic resonance (FMR) was used for the investigation of nickel powders dispersed in a diamagnetic solid matrix. The fine structure of FMR was studied, which was observed against a background of broad featureless FMR lines of conventional unoriented polycrystals. A model is suggested according to which the narrow lines observed appear in the FMR spectra because of jumplike changes in the resonance conditions caused by a sharp change in the magnetization of the sample due to a change in the external magnetic field. In contrast to the Barkhausen effect, the fine structure detected in the FMR spectra in this case is observed in stronger fields characteristic of the processes of magnetization rotation. It is shown that the physical origin of magnetization jumps in this case may be magnetic interparticle interactions as well as complex anisotropy of particles.