J. Phys.: Condens. Matter 13 (5 November 2001) 9897-9911

Surfactant-induced structures in the heteroepitaxial growth of Co on Cu(111)

S Müller1, J E Prieto2,3, T Krämer1,4, C Rath1, L Hammer1, R Miranda2 and K Heinz1
1 Universität Erlangen-Nürnberg, Lehrstuhl für Festkörperphysik, Staudtstr. 7, D-91058 Erlangen, Germany
2 Dpto. Física de la Materia Condensada and Instituto Universitario de Ciencia de Materiales `Nicolás Cabrera', Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid, Spain

Abstract. The growth of Co on Cu(111) with Pb as a surfactant is found to be accompanied by a considerable surface reconstruction of (4 × 4) symmetry induced by the surfactant. Its crystallography was investigated by quantitative low-energy electron diffraction (LEED) for an initial and later stage of growth with deposition of 1.3 monolayer (ML) and 7 ML Co, respectively. In the low coverage case the surface reconstruction is rather similar to that of Pb/Cu investigated earlier. It extends deep into the substrate with simultaneous minimization of the Pb layer buckling. The structure seems to be controlled by dominating fcc-stacking characteristic of this early stage of growth. With further cobalt deposition the type of reconstruction changes. For the 7 ML Co film it is restricted to the Pb and top Co layer only with the buckling of the surfactant layer considerably increased. We discuss that this may be attributed to the slightly different lattice parameters of Cu and Co, though the influences of the different stacking involved cannot be ruled out. The top film layer is always reconstructed during the whole growth which might be responsible for the easy exchange processes which take place during the growth and are essential for the layer-by-layer growth as found earlier.