A possible mechanism for high-temperature superconductivity: application to Bi and Tl compounds

Abstract

We applied our previous theory of high temperature superconductivity to Bi and Tl compounds in this paper. The theory involves the role of electron pairs in the spin singlet of species X⋝ (Bi³⁺ (6S²), Tl(6S²) etc.) and their virtual excited state X₀ (Bi⁵⁺ (6s⁰), Tl³⁺ (6s⁰), etc.) in the pairing interaction of quasiholes. Bi and Tl species provide additional channels of kind (X⋝ X⁰) owing to the charge fluctuations. We treated the two states of these species like a two-level Bose system. We used the pseudospin formalism to calculate the expression for the critical temperature in this paper. We also calculated numerically the value of T_c for Bi and Tl compounds and found a good agreement between theory and experiment.