Spontaneous Fermi surface deformation in the three-band Hubbard model: A variational Monte Carlo study

TL;DR

This study uses variational Monte Carlo methods to investigate spontaneous Fermi surface deformation in the three-band Hubbard model, revealing conditions under which electronic nematicity emerges and its dependence on model parameters.

Contribution

It provides the first variational Monte Carlo evidence for d-wave Fermi surface deformation in the three-band Hubbard model, linking it to intra-unit-cell nematicity.

Findings

dFSD is strongest at half-filling without magnetism.

dFSD disappears at hole doping around 1.15.

Coulomb interactions and charge-transfer energy promote dFSD.

Abstract

We perform a variational Monte Carlo study on spontaneous d-wave form Fermi surface deformation ($d$FSD) within the three-band Hubbard model. It is found that the variational energy of a projected Fermi sea is lowered by introducing an anisotropy between the hopping integrals along the x and y directions. Our results show that the $d$FSD state has the strongest tendency at half-filling in the absence of magnetism, and disappears as the hole concentration increases to $n_h\approx 1.15$. This is qualitatively in agreement with the mean field analysis and the exact diagonalization calculation for the one-band models, and provides a qualitative explanation to the "intra-unit-cell" electronic nematicity revealed by the scanning tunneling microscopy. An analysis of the dependence of $d$FSD on the parameters of the three-band model indicates that the copper on-site Coulomb interaction, the nearest-neighbor copper-oxygen repulsion, and the charge-transfer energy have a remarkable positive effect on $d$FSD.