Effect of oxygen deficiency (δ) on transition temperature of yttrium cuprate superconductors

Abstract

The nature of pairing mechanism as well as transition temperature of yttrium cuprates is discussed using the strong coupling theory. An interaction potential has been developed for the layered structure with two conducting CuO2(a-b) layers in a unit cell. The interaction potential property takes care of electron-electron, electron-phonon and electron-plasmon interactions. Furthermore, the electron- phonon coupling parameter (λ), the modified Coulomb repulsive parameter (μ*) and the 2D acoustic phonon (plasmon) energy as a function of oxygen deficiency is worked out. Finally, the superconducting transition temperature (Tc) is then evaluated by using these coupling parameters and obtained TC = 95(92) K for Y (Yb) Ba2 Cu3 O7-δ superconductors with δ = 0.0. The model parameters estimated from the layered structure approach are consistent with the strong coupling theory. The result deduced on the variation of Tc with δ are in fair agreement with the earlier reported data on yttrium cuprates. The analysis of the above results are discussed.