Quantum fluctuations, pseudogap, and the T=0 superfluid density in strongly correlated d-wave superconductors

Abstract

I study the effect of Coulomb interaction on superconducting order in a d-wave lattice superconductor at T=0 by considering the superconducting saddle point in the two dimensional t-J-U model with an on-site repulsion U. The theory of low energy phase fluctuations around this saddle point is derived in terms of the effective hard-core bosons (representing the density of spin-up electrons and the order parameter phase), interacting with the fluctuating density of spin-down electrons. Whereas the saddle point value of the gap is found to monotonically increase towards half filling, the phase stiffness at T=0 has a maximum, and then decreases with further underdoping. Right at half filling the stiffness vanishes for large U. This argues that the pseudogap phenomenon of the type observed in cuprates is in principle possible without a development of any competing order, purely as a result of growing correlations in the superconducting state. The effects of finite temperature and disorder are discussed qualitatively.

9 RevTex pages, 2 figures; minor corrections in Eqs. 8 and 34, new Figure 2, several typos corrected, more explanations, new and updated references; to appear in Phys. Rev. B

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Cited by in corpus (6)

• When Superconductivity Crosses Over: From BCS to BEC
• Effective theory of high-temperature superconductors
• Superconducting Fluctuation and Pseudogap in Disordered Short Coherence Length Superconductor
• Screening in anisotropic superfluids and the superfluid density in underdoped cuprates
• Effective action for phase fluctuations in d-wave superconductors near a Mott transition
• Electron pairing and evidence of a BCS-BEC crossover in d-wave superconductors