  We demonstrate that in a ferromagnetic substrate, which is continuously
driven out of equilibrium by a field moving with constant velocity $v$, at
least two types of friction may occur when $v$ goes to zero: The substrate may
feel a friction force proportional to $v$ (Stokes friction), if the field
changes on a time scale which is longer than the intrinsic relaxation time. On
the other hand, the friction force may become independent of $v$ in the
opposite case (Coulomb friction). These observations are analogous to e.g.
solid friction. The effect is demonstrated in both, the Ising (one spin
dimension) and the Heisenberg model (three spin dimensions), irrespective which
kind of dynamics (Metropolis spin-flip dynamics or Landau-Lifshitz-Gilbert
precessional dynamics) is used. For both models the limiting case of Coulomb
friction can be treated analytically. Furthermore we present an empiric
expression reflecting the correct Stokes behavior and therefore yielding the
correct cross-over velocity and dissipation.
