FIRST-ORDER VERSUS 2ND-ORDER INTERFACE LOCALIZATION TRANSITION OF THIN ISING FILMS WITH COMPETING WALLS

From extensive Monte Carlo simulations of a lattice gas model we prese nt evidence that the order of the gas-liquid transition of a fluid con fined between ''competing'' walls can change from second to first orde r when the thickness D of the thin film is varied. This situation typi cally arises when the wetting transition of the corresponding semi-inf inite system is first order, and thus permits the study of a tricritic al interface-localization-delocalization transition via control of the film thickness.