Step-induced structural modification of Co thin films deposited on Au(2 3 3) vicinal surface

We report on a step-induced morphological modification in Cobalt thin films (from 5 to 90 monolayers (ML)) on Au(1 1 1) substrates studied by grazing incidence X-ray diffraction (GIXD). When the cobalt film is deposited on the highly stepped Au(2 3 3) substrate its structure is found to be mainly face centered cubic (FCC) whereas its natural bulk structure is hexagonal close-packed (HCP). Relaxation and stacking fault probability have been determined using a simple diffraction model which fits all the GIXD data. A vicinal Co interface including this stacking fault probability and a small rotation of the Co(1 1 1) planes with respect to the Au(1 1 1) planes is proposed which is in exact registry with the Au vicinal surface.