Surface freezing in a liquid eutectic Ga-Bi alloy

Surface freezing in a liquid eutectic Ga-Bi alloy has been studied by secon d harmonic generation and plasma excitation in several cooling and heating cycles at different temperature rates. An ordered solid-like film is observ ed on top of the bulk liquid which forms at a temperature well above the eu tectic temperature. The hysteresis behaviour of crystallisation and melting of this film indicates that this surface phase transition is of first orde r, which is reported for the first time. (C) 2001 Elsevier Science B.V. All rights reserved.