Quantum-size effects on Tc in superconducting nanofilms

An essential property of a high-quality metallic nanofilm is the quantization of the electron spectrum due to dimensional confinement in one direction. Quantum confinement has a substantial impact on the superconducting characteristics and leads to quantum-size variations of the critical temperature T-c with film thickness. We demonstrate that the Bogoliubov-de Gennes equations are able to describe the thickness-dependent T-c in nanofilms, and our results are in good agreement with recent experimental data on Pb flat terraces grown on silicon (Science, 306 (2004) 1915 and Nature Phys., 2 (2006) 173). We predict that the quantum-size oscillations of T-c will be more pronounced for Al.