Prewetting transition on a weakly disordered substrate: Evidence for a creeping film dynamics
Laboratoire Kastler Brossel, Ecole Normale Supérieure
24 rue Lhomond, F75231 Paris cedex 05, France
Accepted: 7 March 2001
We present the first microscopic images of the prewetting transition of a liquid film on a solid surface. Pictures of the local coverage map of a helium film on a cesium metal surface are taken while the temperature is raised through the transition. The film edge is found to advance at constant temperature by successive avalanches in a creep motion with a macroscopic correlation length. The creep velocity varies strongly in a narrow temperature range. The retreat motion is obtained only at much lower temperature, conforming to the strong hysteresis observed for prewetting transition on a disordered surface. Prewetting transition on such disordered surfaces appears to give rise to dynamical phenomena similar to what is observed for domain wall motions in 2D magnets.
PACS: 81.15.Lm – Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids) / 68.15.+e – Liquid thin films / 68.35.Rh – Phase transitions and critical phenomena
© EDP Sciences, 2001