Theory of nonlinear surface spin waves on a pure exchange ferromagnet

In terms of the total energy of a ferromagnet and the Landau-Lifshitz equat ion, the nonlinear surface spin waves in a ferromagnet viith pure nonunifor m exchange anisotropies are studied. It is found that the nonlinear dispers ion relation for these waves is modified by the nonuniform exchange anisotr opy comstants, and the nonlinear excitation appears as surface magnetic sol itons localized near the surface of a crystal. A two-dimensional nonlinear Schrodinger equation for the spin-wave envelope is obtained and the conditi ons for the existence of a single soliton Solution are discussed.