Characterizing the three-orbital Hubbard model with determinant quantum Monte Carlo

TL;DR

This paper uses advanced determinant quantum Monte Carlo simulations to study the three-orbital Hubbard model relevant to cuprate superconductors, revealing orbital-specific behaviors, magnetic ordering, and spectral properties consistent with experiments.

Contribution

It provides a comprehensive characterization of the three-orbital Hubbard model using DQMC, highlighting orbital occupation, magnetic order, and spectral features with comparisons to other numerical methods.

Findings

Doped holes prefer oxygen orbitals

Antiferromagnetic order dominates near undoped state

Predicted charge-transfer gap is smaller than optical gap

Abstract

We characterize the three-orbital Hubbard model using state-of-the-art determinant quantum Monte Carlo (DQMC) simulations with parameters relevant to the cuprate high-temperature superconductors. The simulations find that doped holes preferentially reside on oxygen orbitals and that the ({\pi},{\pi}) antiferromagnetic ordering vector dominates in the vicinity of the undoped system, as known from experiments. The orbitally-resolved spectral functions agree well with photoemission spectroscopy studies and enable identification of orbital content in the bands. A comparison of DQMC results with exact diagonalization and cluster perturbation theory studies elucidates how these different numerical techniques complement one another to produce a more complete understanding of the model and the cuprates. Interestingly, our DQMC simulations predict a charge-transfer gap that is significantly smaller than the direct (optical) gap measured in experiment. Most likely, it corresponds to the indirect gap that has recently been suggested to be on the order of 0.8 eV, and demonstrates the subtlety in identifying charge gaps.