The advantages were highlighted of using point-contact spectroscopy in multi-gap superconductors, both as a fundamental research tool and as a non-destructive diagnostic technique for the optimization of thin-film characteristics. Some results which were of fundamental interest, obtained by directional point-contact spectroscopy in MgB2 single crystals, were first presented. These included the temperature dependence of the gaps and of the critical fields, and the effect of a magnetic field upon the gap amplitudes. It was then shown how point-contact spectroscopy could provide useful information about the surface properties of MgB2 thin films (TC, gap amplitude, clean- or dirty-limit conditions) in view of their optimization for the fabrication of tunnel and Josephson junctions.

Point-Contact Spectroscopy in MgB2 - from Fundamental Physics to Thin-Film Characterization. R.S.Gonnelli, D.Daghero, A.Calzolari, G.A.Ummarino, V.Dellarocca, V.A.Stepanov, S.M.Kazakov, J.Karpinski, C.Portesi, E.Monticone, V.Ferrando, C.Ferdeghini: Superconductor Science and Technology, 2004, 17, S93-100