Electronic States of Small κ Superconducting Alloys

Abstract

The effects of impurities or alloying materials on the electronic states of Superconductors with small GL parameters were studied. The examination was performed on In-Bi, In-Tl, In-Pb, Sn-Bi and Sn-Sb alloys and the superconducting phase diagrams were determined. It was stated that the complete macroscopic description needs the T-H-C space instead of the usual T-H surface. A general formula was calculated for T_c by Green’s function method, which can take into account all effects of diamagnetic and paramagnetic impurities. It was shown that the phase transition of type I superconductivity to type II one is higher than second order. A simple phenomenological model was given for the transition from type II superconductivity into normal state due to increasing additive material content.