Surface melting away from equilibrium

Abstract

A solid-vapor interface is theoretically studied in the vicinity of the triple point, where the liquid phase coexists with the solid and the vapor. We find that surface melting also occurs if the solid-vapor interface moves with constant velocity v as a result of slow evaporation of the crystal. In fact, the thickness of the liquidlike surface layer is found to increase with increasing v. For materials with a low vapor pressure such as Pb, this dynamically induced thickening of the liquidlike surface layer is, however, estimated to be very small. This implies that the interfacial structure observed in recent experiments should closely resemble the equilibrium structure.