Mobility of Bloch walls via the collective coordinate method

We have studied the problem of the dissipative motion of Bloch walls consid ering a totally anisotropic one-dimensional spin chain in the presence of a magnetic field. Using the so-called "collective coordinate method'' we con struct an effective Hamiltonian for the Bloch wall coupled to the magnetic excitations of the system. It allows us to analyze the Brownian motion of t he wail in terms of the reflection coefficient of the effective potential f elt by the excitations due to the existence of the wall. We find that for f inite values of the external field the wall mobility is also finite. The sp ectrum of the potential at large fields is investigated and the dependence of the damping constant on temperature is evaluated. As a result we find th e temperature and magnetic-field dependence of the wall mobility.