Pseudogaps in the 2D half-filled Hubbard model

TL;DR

This paper investigates pseudogaps in the 2D half-filled Hubbard model using quantum Monte Carlo methods, revealing a persistent charge pseudogap with non-Fermi liquid behavior and highlighting methodological biases.

Contribution

It demonstrates the persistence of a charge pseudogap in the thermodynamic limit and compares finite-size and DCA methods in estimating pseudogap width.

Findings

Charge pseudogap persists in the thermodynamic limit.

DCA underestimates pseudogap width; finite-size overestimates.

No spin pseudogap observed at half-filling.

Abstract

We study the pseudogaps in the spectra of the half-filled 2D Hubbard model using both finite-size and dynamical cluster approximation (DCA) quantum Monte Carlo calculations. A charge pseudogap, accompanied by non-Fermi liquid behavior in the self energy, is shown to persist in the thermodynamic limit. The DCA (finite-size) method systematically underestimates (overestimates) the width of the pseudogap. A spin pseudogap is not seen at half-filling.