Nonlinear surface spin waves on ferromagnetic media with inhomogeneous exchange anisotropy

Abstract

The theory of nonlinear surface spin waves in pure-exchange semi-infinite ferrom agnetic media with inhomogeneous exchange anisotropy has been considered by usin g the Landau-Lifshitz equation. For partly pinned pure-exchange ferromagnet, the boun-dary condition for magnatization of this system is derived, and the nonlinear dispersion relation for these waves is obtained. The one-dimensional(stationary wave along the z-direction) and two-dimensional(2D)(travelling wave in the oxy plane) nonlinear Schrdinger equations which are satisfied by the spin -wave envelope amplitude of the magnetization, are derived. It is shown that the amplitude of the magnetization is determined by the 2D nonlinear Schrdinger e quation. From this, we predict that the nonlinear excitation on the surface of m agnetic materials should be of 2D soliton form. For weakly nonlinear spin waves, the possibi-lity of soliton formation on the basis of 2D nonlinear Schrdi nger equation has been discussed in detail.