Preformed Cooper Pairs as Origin of Pseudogap in Cuprates

Abstract

A weak-coupling scenario wherein bosonic preformed electron pairs emerge upon cooling from two-electron correlations can explain the pseudogap phase consisting of segments where a Bogoliubov-like energy-momentum relation gapped spectrum alternates with a normal ungapped one. Bose-Einstein condensation (BEC) of preformed pairs interacting with the background fermions leads to either d- or s wave-like superconducting gaps, the result being sensitive to the magnitude of the total number density of pairs n (B) at which BEC occurs and becomes possible already for a moderately anisotropic s wave pairing of fermions repelling each other via isotropic coulombic forces. The present model is compatible with the coexistence of both pseudogap and of superconductivity phenomena.