A consistent description of the pairing symmetry in hole and electron doped cuprates within the two dimensional Hubbard model

TL;DR

This study uses Quantum Monte Carlo to analyze pairing correlations in the 2D Hubbard model, revealing how doping type influences pairing symmetry and suggesting possible nodeless gap formation.

Contribution

It provides a unified description of pairing symmetry variations in hole- and electron-doped cuprates within the 2D Hubbard model, highlighting the role of band features.

Findings

Hole doping enhances d_{x^2-y^2} pairing correlations.

Electron doping enhances both d_{x^2-y^2} and d_{xy} correlations.

Possible mixing of pairing symmetries leads to a nodeless gap.

Abstract

Quantum Monte Carlo is used to calculate various pairing correlations of the 2D Hubbard model possessing band features experimentally observed in the cuprates. In the hole-doped case, where the Fermi level lies close to the van Hove singularities around $(0,\pi)$, the d$_{x^2-y^2}$ pairing correlation is selectively enhanced, while in the electron-doped case, where the singularities are far below the Fermi level and the Fermi surface runs through $(\pm \pi/2,\pm \pi/2)$, both d$_{x^2-y^2}$ and d$_{xy}$ correlations are enhanced with the latter having a $\sqrt{2}\times \sqrt{2}$ structure. The two pairing symmetries can mix to result in a nodeless gap.