HIGH-TC SUPERCONDUCTING THIN-FILMS - AN ANALYSIS OF REFLECTANCE SPECTRA

The strong contribution of the substrate to the reflectance of superconducting thin films prevents the use of standard Kramers-Krönig transformations to derive the superconductor optical conductivity. This quantity has to be obtained by canonical procedures, which imply the knowledge of the substrate optical conductivity. Two systems are discussed: a metallic BSCCO thin film deposited on MgO and an insulating one on ZrO2.