Shpyrko, Oleg G.Streitel, ReinhardBalagurusamy, Venkatachalapathy S. K.Grigoriev, Alexei Yu.Deutsch, MosheOcko, Benjamin M.Meron, MatiLin, BinhuaPershan, Peter2011-02-162007Shpyrko, Oleg G., Reinhard Streitel, Venkatachalapathy S. K. Balagurusamy, Alexei Yu. Grigoriev, Moshe Deutsch, Benjamin M. Ocko, Mati Meron, Binhua Lin, and Peter S. Pershan. 2007. Crystalline surface phases of the liquid Au-Si eutectic alloy. Physical Review B 76(245436).1098-0121http://nrs.harvard.edu/urn-3:HUL.InstRepos:4726291A two-dimensional crystalline layer is found at the surface of the liquid eutectic Au82Si18 alloy above its melting point TM=359 °C. Underlying this crystalline layer, we find a layered structure, 6–7 atomic layers thick. This surface layer undergoes a first-order solid-solid phase transition occurring at 371 °C. The crystalline phase observed for T>371 °C is stable up to at least 430 °C. Grazing-incidence x-ray diffraction data at T>371 °C imply lateral order comprising two coexisting phases of different oblique unit cells, in stark contrast with the single phase with a rectangular unit cell found for low-temperature crystalline phase, 359 °C<T<371 °C.en-USJournal Article10.1103/PhysRevB.76.245436