REENTRANT WETTING TRANSITION OF A ROUGH WALL

A 2D model describing depinning of an interface from a rough, self-aff ine substrate, is studied by transfer matrix methods. The phase diagra m is determined for several values of the roughness exponent, zeta(S), of the attractive wall. For all zeta(S) > 0 the following scenario is observed. In first place, in contrast to the case of a flat wall (zet a(S) = 0), for wall attraction energies between zero and a zeta(S)-dep endent positive value, the substrate is always wet. Furthermore, in a small range of attraction energies, a dewetting transition first occur s as T increases, followed by a wetting one. This unusual reentrance p henomenon seems to be a peculiar feature of self-affine roughness, and does not occur, e.g., for periodically corrugated substrates.