Influence of a Finite Tc on Enhanced Superconductivity Near the Metal/Insulator Transition

We adapted the BCS equation for T _c so that it applies to disordered conductors near the metal/insulator transition (MIT). The resulting expression for T _c as a function of the conductivity accounted quite well for several disparate classes of superconducting materials near the MIT disordered metals, oxide conductors (including high-T _c superconductors), semiconducting materials, organic conductors, and C₆₀]. This function, however, was applicable only to situations for which T _c was zero in the pure limit—which was the case for the data chosen. This paper extends the model to the nonzero case and compares the predictions to the appropriate data.