THEORY OF RETARDATION OF MAGNETIC DOMAIN-WALLS IN RHOMBIC MAGNETIC-MATERIALS

We calculate the retardation of a magnetic soliton describing a magnet ic domain wall by using the generalized phenomenological theory of rel axation. We show that in this theory, based on the real dynamical symm etry of magnetic materials, the dissipation function has a different s tructure for high and low wall velocities. Finally, we calculate the v iscous force of the wall in the Walker model and show that certain fea tures, not discussed in the literature, emerge even when the generaliz ed theory is applied to this simple model. In particular, the dependen ce of the viscous friction force on the wall velocity may be highly no nlinear and regions of unstable motion may appear. (C) 1997 American I nstitute of Physics.