Dynamic damping of domain walls in weak ferromagnets

A microscopic theory is developed for the energy dissipation of a moving domain wall of a weak ferromagnetic by interaction between the wall and thermal magnons. Different dynamic regimes are considered - translational wall motion and propagation of flexure waves along the wall. The special roles of small system-energy terms that disturb the soliton character of the domain wall, and of the fact that the wall does not reflect the magnons with which it interacts, are pointed out. A phenomenological equation that describes consistently the domain-wall dynamics and relaxation is proposed on the basis of the microscopic calculations