EXPANSION OF ULTRATHIN COBALT FILMS IN (AU-CO) MULTILAYERS MEASURED BY DIFFRACTION METHODS

In this paper, we present the results obtained from diffraction techniques, which give information on the structure of (00.1) h.c.p. cobalt thin films embedded in (111) fc.c. gold layers. Electron and X-ray experiments were performed on gold-cobalt multilayers with smooth interfaces; they both show an expansion of the cobalt cell in the direction perpendicular to the interfaces; a smaller isotropic expansion in the interface plane is also shown, leading to a volume expansion and to a distortion of the cobalt cell. This expansion is found to be linked with the cobalt thickness and the nature of the spacer material.