Role of gold segregation in the growth mode and the morphology of Fe/Au(0 0 1) magnetic thin films

The growth mode of iron on Au(0 0 1) surface at room temperature has been studied by means of photoelectron spectroscopy and scanning photoemission microscopy. The analysis of Au4f core level shifts reveals the segregation of gold atoms during the growth, leading for high coverage to the floating of Au surface layer burying Fe thin film and AuFe interfacial alloy. The formation of such segregating layer is coherent with energetic criteria (low gold surface energy, negative interfacial mixing energy, size effect,…). The synergy between these effects may favour the intermixing at the interface and the gold segregation. Photoemission microscopy measurements have been carried out to characterize local morphological and compositional inhomogeneities. The growth proceeds via the segregation of small three-dimensional AuFe gold islands surrounded by a flat Fe/Au region.