Metal-insulator transition in the ground-state of the three-band Hubbard model at half-filling

TL;DR

This study uses advanced quantum Monte Carlo methods to analyze the ground-state phase transition in the three-band Hubbard model, revealing a transition from an antiferromagnetic insulator to a paramagnetic metal as the charge-transfer energy decreases.

Contribution

First high-accuracy quantum Monte Carlo analysis of the three-band Hubbard model's ground state, demonstrating a quantum phase transition driven by charge-transfer energy.

Findings

Identified a quantum phase transition at Δ ≈ 3 eV.

Provided benchmark magnetic correlation and charge gap results.

Showed the model's phase change from insulator to metal.

Abstract

The three-band Hubbard model is a fundamental model for understanding properties of the Copper-Oxygen planes in cuprate superconductors. We use cutting-edge auxiliary-field quantum Monte Carlo (AFQMC) methods to investigate ground state properties of the model in the parent compound. Large supercells combined with twist averaged boundary conditions are studied to reliably reach the thermodynamic limit. Benchmark quality results are obtained on the magnetic correlations and charge gap. A key parameter of this model is the charge-transfer energy $\Delta$ between the Oxygen p and the Copper d orbitals, which appears to vary significantly across different families of cuprates and whose ab initio determination is subtle. We show that the system undergoes a quantum phase transition from an antiferromagnetic insulator to a paramagnetic metal as $\Delta$ is lowered to 3 eV.