CHARACTER OF THE PHASE-TRANSITION IN THIN ISING FILMS WITH COMPETING WALLS

By extensive Monte Carlo simulations of a lattice gas model we have studied the controversial nature of the gas-liquid transition of a fluid confined between two parallel plates that exert competing surface fields. We find that the transition is shifted to a temperature just below the wetting transition of a semi-infinite fluid but belongs to the two-dimensional Ising universality class. In between this new type of critical point and bulk criticality, a response function xnnmax varying exponentially with D is observed, 2lnχnnmaxD=-1, where is a new length characterizing interfaces. © 1995 The American Physical Society.