Statics and dynamics of an interface in a temperature gradient.

Abstract

Here we are primarily concerned with the effect of a (normally oriented) temperature gradient on an equilibrium interface separating coexisting phases in a symmetric binary system below its critical temperature. In such a system, the temperature couples ``weakly'' to the order parameter and does not favor either of the potentially coexisting bulk phases. Nonetheless, for a large system, there can be a dramatic effect and a failure of a linear response owing to the breaking of translational invariance by the spatially varying temperature. Two types of boundary conditions on the order parameter, natural and ``topological,'' are used. The structure of the effective free energy, nonconserved dynamics, and the Langevin equation for the collective coordinate specifying the interface position are analyzed.