Nonlinear Magnetization Waves and Solitons in a Paramagnet with a Dipole Interaction

Abstract

Based on a microscopic approach, we have derived equations for the local magnetization dynamics of a spin system coupled by a dipole–dipole interaction in a uniform magnetic field in the continuum approximation. Using the generalized method of multiple scales, we have found the corrections to the Larmor precession frequency of the magnetic moments due to the interparticle interaction, which lead to a broadening of spectral lines and the formation of satellites far from the Larmor frequency. We have derived nonlinear equations for the magnetization amplitude in higher expansion orders, which admit wave and soliton solutions. We have analyzed the influence of the nonsecular part of the dipole–dipole interaction on the stability of solitons and determined the conditions for their existence.