Wetting Transition Far from Thermal Equilibrium

The interaction of a bulk phase of a system with a wall or a substrate may result in very interesting wetting phenomena. In certain cases a second phase which is preferentially attracted to the wall may be formed, and phase transitions, in which the thickness of of the surface layer diverges may take place. These and related phenomena have been extensively studied in the past in systems under thermal equilibrium conditions. Here, wetting phenomena in systems driven out of thermal equilibrium will be discussed. A simple two-dimensional model of a phase growing on a substrate is introduced. The dynamical rules according to which the model evolves do not obey detailed balance resulting in a non-equilibrium steady state. The model exhibits a wetting transition which may be viewed as an unbinding transition of an interface from a wall. The nature of the transition, possible universality classes and crossover behaviour of various physical quantities such as the interface width and the zero level occupation are discussed