d-Wave Pairing in the Presence of Long-Range Coulomb Interactions

TL;DR

This study investigates how long-range Coulomb interactions affect d-wave pairing in a 2D extended Hubbard model, finding that moderate long-range repulsions do not suppress pairing, but large ones induce charge density waves.

Contribution

It provides a detailed analysis of the robustness of d-wave pairing against long-range Coulomb interactions within the extended Hubbard model.

Findings

d_(x^2 - y^2) pairing remains stable with moderate long-range Coulomb interactions.

Large Coulomb repulsions (>~ 0.25U-0.4U) suppress pairing due to charge density wave formation.

Long-range interactions only significantly affect pairing at high repulsion strengths.

Abstract

The one-band extended Hubbard model in two dimensions near band-filling 1/2 is solved in the fluctuation exchange approximation, including the long-range (1/r) part of the Coulomb interaction, up to 4th neighbor distance. Our results suggest that d_(x^2 - y^2) pairing in the Hubbard model is robust against the inclusion of long-range Coulomb interactions with moderate 1st neighbor repulsion strength V_1. d_(x^2 - y^2) pairing is suppressed only at large V_1 (>~ 0.25U-0.4U), due to incipient charge density wave instabilities.