Degenerated nuclear magnetostatic modes in ferromagnets

The detailed calculations of dependence of the frequency of oscillations on the external magnetic field and on the shape of ferromagnet sample with interacting electronic and nuclear subsystems were done. Such system possesses a discrete number of eigenfrequencies of precession of magnetization. It is shown that these magnetostatic eigenmodes can be degenerated, i.e. different modes can have the same frequency. The dependence of these degenerated modes on the sample shape is investigated. It is shown that the properties of magnetization precession and even the number of eigenmodes depend on the external magnetic field and on the shape of the sample. These effects may produce specific features on the NMR spectra of magnetic materials.