SURFACE ORDER-DISORDER TRANSITION IN THE SOLID SOLUTION Cu3 Au

Overview & Synopsis

Surface criticality of semi-infinite systems which undergo first order phase transitions is considered. We present Synchrotron-X superlattice scattering intensities from the Cu3Au(100) surface, where the surface sensitivity is achieved by the scheme of total external reflection. The quantitative analysis of the temperature- and scattering depth-dependence of the evanescent (001) superlattice peak proofs the continous behaviour of the surface order parameter and the existence of a disordered "wetting layer" below the transition temperature T0. The observations are consistent with the assumption of a logarithmic growth of this surface-induced disordered region when T0 is approached.