Soliton Excitations in the Compressible Heisenberg Spin Chain: A General Approach11The project supported by National Natural Science Foundation of China and Foundation of Doctoral Education of China

Abstract

A general approach is given for the nonlinear excitations in the compressible Heisenberg ferromagnetic chain in coherent-state representation. It is shown that the relative ratio of to is very important for determining the nonlinear modified terms of the equations of motion. (S is the spin length) and (a is the lattice constant and is the characteristic wavelength of the excitations) are two small dimensionless parameters used in the semiclassical approximation and in the long wavelength approximation, respectively. In the case of , the reduced equations of motion are solved exactly and spin soliton and elastic kink solutions are obtained. The other cases of the relation between and are also discussed and the solitary wave solutions are also given. The result obtained by Ferrer, as a special case, has been included in our approach.