Soliton dynamics in 3D ferromagnets

We study the dynamics of solitons in a Landau-Lifshitz equation describing the magnetization of a three-dimensional ferromagnet with an easy axis anis otropy. We numerically compute the energy dispersion relation and the struc ture of moving solitons, using a constrained minimization algorithm. We com pare the results with those obtained using an approximate form for the movi ng soliton, valid in the small momentum limit. We also study the interactio n and scattering of two solitons, through a numerical simulation of the (3 + 1)-dimensional equations of motion. We find that the force between two so litons can be either attractive or repulsive depending on their relative in ternal phase and that in a collision two solitons can form an unstable osci llating loop of magnons. (C) 2001 Elsevier Science B.V. All rights reserved .