Superconductivity in ultra-thin CoSi2 epitaxial films

The first results on the superconducting properties of ultra-thin epitaxial CoSi 2 films are reported. The metal films are obtained by solid phase epitaxy under ultra high-vacuum conditions, with thicknesses ranging from 600 A down to 50 A. These films are stable against temperature cycling from 350 mK up to room temperature and superconducting for thicknesses down to 100 A. Results showing a reduction of the transition temperature and variations of the critical magnetic field with decreasing film thicknesses are presented. Furthermore, for very low film thicknesses (i.e. 100 A), an intermediate plateau is observed in the resistivity versus temperature curve. The physical origin of these phenomena is briefly discussed Preparation de couches minces de 50 a 600 A d'epaisseur, stables lors de cycles thermiques de 350 mK jusqu'a la temperature ambiante et supraconducteurs pour des epaisseurs superieures a 100 A. Diminution de la temperature critique et variations du champ magnetique critique quand l'epaisseur diminue. Observation d'un plateau dans la courbe de resistivite en fonction de la temperature pour la couche de 100 A