First-order transition in systems of finite thickness.

Abstract

Film systems, limited by two parallel disrupting surfaces and undergoing a first-order bulk transition, are shown to possess a number of specific features essentially governed by the ratio of the film thickness $L$ to the "characteristic" length ${L}_{0}$ of the transition. For disordering boundaries, it is found that (1) the transition temperature scales as ${L}^{\ensuremath{-}1}$ for $\frac{L}{{L}_{0}}\ensuremath{\gg}1$, (2) the continuous transition of the surface order parameter, predicted to occur in semi-infinite systems, transforms into a weak first-order transition, and (3) below a critical thickness, no transition occurs. Comparisons with experimental systems are discussed.