Revisiting superconductivity in the extended one-band Hubbard model: Pairing via spin and charge fluctuations

Abstract

The leading superconducting instabilities of the two-dimensional extended repulsive one-band Hubbard model within spin-fluctuation pairing theory depend sensitively on electron density, band, and interaction parameters. We map out the phase diagrams within a random-phase-approximation spin- and charge-fluctuation approach, and find that while B1g (dx2−y2) and B2g (dxy) pairing dominates in the absence of repulsive longer-range Coulomb interactions VNN, the latter induces pairing in other symmetry channels, including, e.g., A2g (g-wave), nodal A1g (extended s-wave), or nodal Eu (p-wave) spin-triplet superconductivity. At the lowest temperatures, transition boundaries in the phase diagrams between symmetry-distinct spin-singlet orders generate complex time-reversal symmetry broken superpositions. By contrast, we find that boundaries between singlet and triplet regions are characterized by first-order transitions. Finally, motivated by recent photoemission experiments, we have determined the influence of an additional explicitly attractive nearest-neighbor interaction, VNN<0, on the superconducting gap structure. Depending on the electronic filling, such an attraction boosts Eu (p-wave) spin-triplet or B1g (dx2−y2) spin-singlet ordering.

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