An x-ray scattering study of the morphology of the Pt(001) surface reveals that below 1820 K it is atomically smooth on length scales exceeding 5000 Å. However, above 1820 K the Pt(001) surface is rough. Specifically, the scattering near the specular condition is diffuse, and may be modeled using a height-height correlation function which diverges logarithmically at large distances. Our data suggest that the average separation between thermally generated steps is many lattice constants.

• Received 6 April 1992

DOI:https://doi.org/10.1103/PhysRevLett.69.941