Structure and growth mode of epitaxial Co/Au(111) magnetic thin films.

The growth mode and the structure of Co layers deposited at room temperatur e (RT) on a Au(lll) single crystal has been studied using core level photoe mission spectroscopy (CL-PES) and surface X-ray absorption spectroscopy (SE XAFS). The analysis of the Au 4f(7/2) photoemission line for different Co c overages provides evidence of an island growth mode with the presence of a slight interdiffusion process at the interface. The polarization dependence of the XANES and EXAFS spectra, taken at the Co K-edge, shows clearly a he xagonal stacking for films thicker than 4ML. The analysis of the first near est neighbour shell shows that this hexagonal structure is very close to th at of the Co hcp bulk: the cobalt films do not grow in a coherent epitaxy o n the Au(lll) surface and they are then not strongly strained. Thus, we can exclude a magnetoelastic contribution to the perpendicular magnetic anisot ropy existing in this system. (C) 1999 Elsevier Science B.V. All rights res erved.