STATICS AND DYNAMICS OF AN INTERFACE IN A TEMPERATURE-GRADIENT

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. © 1995 The American Physical Society.