The effects of hybridization on Cooper-pair binding energy in an intra-band model of superconductivity

• We found a dependence of the Cooper pair size in function of the hybridization V   for T=0T=0.
• The ω‾2(0) branch is the pair binding energy for intra-band case in the BEC limit.
• We obtain an expression for the pair binding energy as a function of even powers of V.
• We relate the doping parameter as a function of V for the La2 − xSrxCuO4 compound.

In this paper we analyze the effects of electron band hybridization in a superconducting material studying the effects on the binding energy of the Cooper pairs and on their size. We adopt a multi-band model that provides the intra-band pairing correlation functions. The hybridization can be tuned by an externally applied pressure or doping, and couple both bands acting to suppress the superconducting gap amplitude. Our analysis extends for all ranges of interactions coming from the usual BCS limit (weak coupling) going to the BEC limit of Cooper pairs (strong coupling) where these pairs become an effective bosonic particle. Our results show the dependence of the Cooper-pair binding energy and size as a function of the hybridization for T=0T=0. We propose a theoretical description for the intra-band binding-energy of the effective bosons in the BEC limit as a function of the hybridization. We also propose a description for the dependence of doping parameter as a function of the hybridization for the La2 − xSrxCuO4 compound.