Depinning by Quenched Randomness

An interface attracted by weaker bonds to a wall can be depinned by quenched impurities in the bulk as well as by thermal fluctuations. Exact calculations in two dimensions indicate that the depinning transition with randomness is characterized by a discontinuous specific heat and a quadratic divergence of the localization length. Numerical simulations indicate delocalization by randomness in cases where there is no analogous depinning by thermal fluctuations, e.g., as in an interface bound to a strip of weak bonds in the bulk, or for two attracting interfaces.