Direct observation of scaling by high-resolution low-energy electron diffraction: O on Mo(110).

Abstract

The critical behavior of the order-disorder transition in the (2\ifmmode\times\else\texttimes\fi{}2) lattice of oxygen on the (110) molybdenum surface is studied by low-energy electron diffractometry with a coherence length of about 600 A\r{}. The critical exponents \ensuremath{\eta}, \ensuremath{\gamma}, \ensuremath{\nu}, and \ensuremath{\beta} of a system which belongs to the universality class of the XY model with cubic anisotropy are extracted for the first time by a new method based on the general scaling properties of the correlation function. \ensuremath{\eta} is found to be abnormally large for Tg${T}_{c}$ and T dependent, approaching the value 0.25 for T\ensuremath{\rightarrow}${T}_{c}$. \ensuremath{\gamma}, \ensuremath{\nu}, and \ensuremath{\beta} have the (T independent) values 1.20\ifmmode\pm\else\textpm\fi{}0.10, 0.84\ifmmode\pm\else\textpm\fi{}0.07, and 0.19\ifmmode\pm\else\textpm\fi{}0.02, respectively.