Surface-melting-induced preroughening

Preroughening (PR) of a crystal surface can be induced by the tendency of t he surface to melt. We show this analytically in a generalized solid-on-sol id model and numerically by simulating the surface as an interface in the 3 D N-state lattice Potts model, which for large enough N is shown to exhibit PR, roughening, and surface melting. The onset of PR is linked to the appe arance of liquidlike signatures in the surface layer, and can be either con tinuous or first order. We suggest that this physics provides the natural e xplanation of the first-order PR of rare-gas-solid (111) surfaces.