The results of a synchrotron X-ray scattering study of thermal disordering of the 1 x 2 reconstructed (110) surface were presented. By observing the temperature dependence of the in-plane superlattice and integral-order surface peaks, as well as the (110) specular reflectivity, it was found that, at 735K, the 1 x 2 surface underwent a reversible deconstruction transition that was characterized by the proliferation of compact antiphase defects; with no measurable change in the density of surface steps. This transition was described by critical exponents which were close to those that characterized a 2-dimensional Ising transition. It was also found that, before reaching 784K, there was a significant increase in the density of surface steps, of the type that was associated with surface roughening. This suggested that the (110) surface disordered via a 2-step process (deconstruction followed by roughening), where the difference between the 2 transition temperatures was less than 50K.

D.T.Keane, P.A.Bancel, J.L.Jordan-Sweet, G.A.Held, A.Mak, R.J.Birgeneau: Surface Science, 1991, 250[1-3], 8-16