LEED and EXAFS study of the crystallographic structure of Cu/c(2 × 2)MnCu(1 0 0) slab

We report the study of the crystallographic structure of Cu/Mn/Cu slabs performed combining low energy electron diffraction and extended X-ray fine structure techniques. The copper is found to grow epitaxially on the c(2 × 2)MnCu(1 0 0) surface alloy. The detailed EXAFS study performed at room temperature and 90 K reveals that, within the experimental uncertainty, the adsorption of Cu on the surface reconstruction destroys the well known Mn corrugation present in the surface alloy. As a consequence, the Cu/Mn/Cu slabs are formed by the following sequence p(1 × 1)Cu/Mn50%Cu50%Cu(1 0 0) where Mn atoms occupy the cubic face centred sites in a truly two-dimensional alloy.