Dynamics of Interface Depinning in a Disordered Medium

The motion of an interface in a disordered medium driven by a constant force is one of the paradigms of condensed matter physics. Well known examples are domain walls in random magnets1 and interfaces between two immiscible fluids pushed through a porous medium2. Closely related problems include impurity pinning in type-II superconductors3 and in charge-density waves (CDWs)4. Despite the importance of these problems, significant progress has been made only recently by Nattermann et al. for interface motion5 (see also6) and by Narayan and Fisher for CDWs7.