Light scattering study of surface freezing and surface viscoelasticity in a eutectic liquid Ga–Bi alloy

Surface freezing in a metallic liquid, the eutectic Ga–Bi alloy, has been studied for the first time by capillary wave spectroscopy at various wave numbers and temperatures. The surface freezing transition is marked by a sharp drop of the surface tension σ by 25 mJ m−2 and a hysteresis behaviour indicating a first-order interfacial phase transition. Analysis of the capillary wave spectra yields information on the surface excess viscoelastic modulus governing shear normal to the surface plane which is found to be consistent with a metallic solid-like surface freezing film on top of the eutectic Ga–Bi alloy.