Surface and near surface structure of Fe-Co layers by scattering-interference of primary electrons

We studied the Co/Fe bi-and multilayer growth on Fe single crystal using the primary-beam diffraction modulated electron emission (PDMEE) technique. This approach enables a chemical selected structural characterization of both surface and buried layers and interfaces to be performed. Co growth on the Fe(001) surface was studied in the 3-70 ML coverage range. The transition from the initial epitaxial bcc phase of the Co film to the stable hcp phase was found to occur rather abruptly at 25-30 ML coverage, a value larger than previously reported in the literature. Subsequent Fe deposition on the Co hcp film recovers the bcc structure in the sandwiched Co layer. However, removal of the Fe epilayer by mild sputtering results again in an hcp Co film.