INTERFACE DEPINNING FROM WEDGES WITH A CENTRAL RIDGE

The depinning properties of a fluctuating interface near 2D and 3D wedges with a central ridge are studied by discrete models with short range interactions. The calculations demonstrate that, in both cases, depinning take place in two stages: i) a continuous filling-like transition in the pure wedge-like components of the system; ii) a final discontinuous jump from the central ridge. In 2D an exact transfer matrix approach shows that, in the thermodynamic limit, the threshold of the depinning from the central ridge coincides with the one corresponding to the continuous filling transition. In 3D, on the contrary, accurate Metropolis Monte Carlo simulations show that the two transitions are separated by a finite gap. The mechanism at the basis of the phenomenon is studied in detail and, in 2D, the whole interface phase diagram and free energy profiles are provided. The physical scenario emerging from these results is discussed also in relation with the problem of the wetting transition in the case of random rough walls.