Observations on the (111) surface of Ge crystal at elevated temperatures have been made by low-energy-electron diffraction with position-sensitive detection. The results indicate that the outermost few atom double layers lose lateral crystalline order in a continuous phase transition 150 K below the bulk melting temperature.

• Received 21 March 1986

DOI:https://doi.org/10.1103/PhysRevLett.58.1437