Surface-Melting-Induced Preroughening

Preroughening (PR) of a crystal surface can be induced by the tendency of the surface to melt. We show this analytically in a generalized solid-on-solid model and numerically by simulating the surface as an interface in the 3D $N$-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 appearance of liquidlike signatures in the surface layer, and can be either continuous or first order. We suggest that this physics provides the natural explanation of the first-order PR of rare-gas-solid (111) surfaces.