d-wave superconductivity in the presence of a near neighbor Coulomb repulsion

TL;DR

This study uses quantum Monte Carlo simulations to examine how near neighbor Coulomb repulsion affects d-wave superconductivity in a doped extended Hubbard model, revealing its robustness up to a certain repulsion strength.

Contribution

It demonstrates that d-wave pairing remains stable against near neighbor Coulomb repulsion up to half the on-site repulsion, highlighting the retarded nature of pairing.

Findings

d-wave pairing is weakly suppressed when V < U/2

pairing stability is due to the retarded nature of pairing

large momentum charge fluctuations suppress pairing near V ≈ U/2

Abstract

Dynamic cluster quantum Monte Carlo calculations for a doped two-dimensional extended Hubbard model are used to study the stability and dynamics of $d$-wave pairing when a near neighbor Coulomb repulsion $V$ is present in addition to the on-site Coulomb repulsion $U$. We find that $d$-wave pairing and the superconducting transition temperature $T_c$ are only weakly suppressed as long as $V$ does not exceed $U/2$. This stability is traced to the strongly retarded nature of pairing that allows the $d$-wave pairs to minimize the repulsive effect of $V$. When $V$ approaches $U/2$, large momentum charge fluctuations are found to become important and to give rise to a more rapid suppression of $d$-wave pairing and $T_c$ than for smaller $V$.