Proximity effects in superconducting heterostructures

The overlayer of metallic thin films on top of an s-wave superconducting substrate is studied by the numerical solution of the fully relativistic Kohn-Sham-Bogoliubov-de Gennes equations via multiple scattering methods. We briefly describe the methodology which allows for a material-specific calculation of the Andreev band structure. We discuss the relation of the effective pair interaction, the anomalous charge density and the induced superconducting gap in heterogeneous systems. Taking Au/Nb films as an example, we also show how surface and interface states behave in such systems and study the formation of the superconducting gap in one-dimensional impurity systems.