EFFECT OF OXYGEN DEFICIENCY (DELTA) ON TRANSITION-TEMPERATURE OF YTTRIUM CUPRATE SUPERCONDUCTORS

The nature of pairing mechanism as well as transition temperature of y ttrium cuprates is discussed using the strong coupling theory. An inte raction potential has been developed for the layered structure with tw o conducting CuO2(a-b) layers in a unit cell. The interaction potentia l properly takes care of electron-electron, electron-phonon and electr on-plasmon interactions. Furthermore, the electron-phonon coupling par ameter (mu), the modified Coulomb repulsive parameter (lambda) and th e 2D acoustic phonon (plasmon) energy as a function of oxygen deficien cy is worked out. Finally, the superconducting transition temperature (T-c) is then evaluated by using these coupling parameters and obtaine d T-c = 95(92)K for Y(Yb)Ba2Cu3O7-delta superconductors with delta = 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 T-c with delta are in fair agreement with the earlie r reported data on yttrium cuprates. The analysis of the above results are discussed.