Perturbed soliton spin excitations by EM-field in ferromagnetic medium

We study nonlinear spin excitations in the form of perturbed solitons in a one dimensional inhomogeneous bilinear anisotropic Heisenberg ferromagnet and an anisotropic homogeneous biquadratic ferromagnet in the classical continuum limit when acted upon by an electromagnetic(EM)-field. Using a reductive perturbation method, we deduce the associated Landau-Lifshtiz equations coupled with Maxwell's equations to perturbed nonlinear Schroedinger equations. A perturbation analysis carried out in both cases shows that the EM-field excites the magnetization of the medium in the form of solitons with small fluctuations.