  We report the observation of a premelting transition at chemically sharp
solid-liquid interfaces using molecular-dynamics simulations. The transition is
observed in the solid-Al/liquid-Pb system and involves the formation of a
liquid interfacial film of Al with a width that grows logarithmically as the
bulk melting temperature is approached from below, consistent with current
theories of premelting. The premelting behavior leads to a sharp change in the
temperature dependence of the diffusion coefficient in the interfacial region,
and could have important consequences for phenomena such as particle
coalescence and shape equilibration, which are governed by interfacial kinetic
processes.
