Reentrant Wetting Transition of a Rough Wall

Abstract

A $2D$ model describing depinning of an interface from a rough, self-affine substrate, is studied by transfer matrix methods. The phase diagram 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 (${\zeta }_S=0$), for wall attraction energies between zero and a ${\zeta }_S$-dependent positive value, the substrate is always wet. Furthermore, in a small range of attraction energies, a dewetting transition first occurs as T increases, followed by a wetting one. This unusual reentrance phenomenon seems to be a peculiar feature of self-affine roughness, and does not occur, e. g., for periodically corrugated substrates.

16 pages, 3 postscript figures included in the text, REVTeX. Submitted to Physica A