Adsorption site, growth, and structure of Co on Cu(111) determined by multiple-scattering analysis of x-ray-absorption spectra

The growth of cobalt on a Cu(111) single crystal is studied using x-ray-absorption spectroscopy. A polarization-dependent multiple-scattering analysis up to the fourth shell of neighbors using the feff code clearly shows that the thick films have a local hcp stacking (ABAB planes) and not the fcc stacking (ABCABC) of the substrate. Moreover, we determine that on a C surface type of the ABC Cu substrate, the Co atoms are first adsorbed on A sites, the second layer on B sites continues the Cu lattice, but the third Co layer already starts a hcp stacking, by mainly choosing A sites again.