Superconductor-Insulator Transitions in Pure Polycrystalline Nb Thin Films

International audienceWe report on a study of the transport properties of Nb thin films. By varying the thickness of the films from 263 angstrom to 25 angstrom, we observed a depression of the superconductivity. Magnetic field was also applied up to 6 T, inducing the disappearance of the superconductivity and the onset of an insulating behavior. The results were compared to those we have already obtained on a highly disordered system, a-NbxSi1-x, to understand whether the same mechanisms for the disappearance of the superconductivity could be at play in pure metallic thin films and in highly disordered systems