Amplification of nuclear magnetostatic oscillations in ferromagnets

The paper is devoted to the problem of coupled electron-nuclear oscillations in ferromagnets of spheroidal shape with the frequencies in the vicinity of ferromagnetic and nuclear magnetic resonance. In this case, the spin-wave dynamic is described in the framework of the phenomenological model,the considered oscillations are the magnetostatic waves and satisfy the magnetostatic boundary conditions. The spectrum of oscillations represent a discrete set of eigenmodes, and the frequencies of some of them are obtained analytically. The amplification factor of magnetic field acting to the nuclear subsystem is calculated. The dependencies of amplification factor on the shape of a ferromagnetic sample and on the eigenfrequencies are investigated.