Electronic pairing mechanism and superconducting gap in high-Tc superconductors

Abstract

We investigate the effects of electronic pairing mechanisms in high-Tc superconducting oxides on the isotope effect and the superconducting gap. With the assumption of the coexistence of phonon and electronic mechanisms for electron pairing, we calculate coupling parameters and find that the electron-phonon coupling constants are much smaller compared with the excitonic contributions. For high frequency electronic mechanisms with energy cutoffs above 0.1 eV, we find the BCS-like values for the gap such that 2Δ0kbTc=3.56 to 4.02. suggesting that a large gap is unlikely for the electronic pairing mechanism.