Nonlinear oscillations of the magnetization in small cylindrical ferromagnetic particles

The radially symmetric nonlinear oscillations of the magnetization in small cylindrical particles of a ferromagnet are considered in the cases of free and fixed boundary conditions at the lateral surface of the particles. It is found that even for nonlinear oscillations of small amplitude the depend ence of the frequency on the amplitude of the oscillations is rather compli cated and can include a series of bifurcations. The character of the oscill ations depends substantially on the boundary conditions; for example, for f ree boundary conditions the solutions exhibit bifurcations that are not pre sent in the case of fixed boundary conditions. We discuss the possibilities for generalizing the results to the case of oscillations in a cylinder wit h a more complicated angular dependence and to the case of radially symmetr ic oscillations in a spherical particle. (C) 2001 American Institute of Phy sics.