Thermal evolution of single-particle spectral function in the half-filled Hubbard model and pseudogap

TL;DR

This paper investigates the pseudogap phenomena in the half-filled Hubbard model, revealing temperature-dependent spectral features and momentum-space behavior using advanced Monte Carlo simulations.

Contribution

It introduces a parallelized cluster Monte Carlo method to accurately compute momentum-resolved spectral functions in large lattices, elucidating pseudogap features.

Findings

Pseudogap features appear between temperatures T_N and T^*.

Peak-to-peak separation varies along the Fermi surface.

Method achieves near finite-size effect-free results on large lattices.

Abstract

In the half-filled one-orbital Hubbard model on a square lattice, we find pseduogap features in the form of two-peak structures associated with the momentum-resolved spectral function, which exists within the temperature window $T_N \lesssim T \lesssim T^*$. $T^*$ is the temperature below which there exists a well-formed dip in the density of state. Inside the window $T_N \lesssim T \lesssim T^*$, the peak-to-peak separation in the two-peak structure of the momentum-resolved spectral function rises on moving away from the point ($\pi/2, \pi/2$) along the normal state Fermi surface towards $(\pi, 0)$, a behavior remarkably similar to what is observed in the pseudogap phase. We unveil these features by using a parallelized cluster-based Monte-Carlo method for simulating the magnetic order parameter fields on a superlattice, which enables us to access the momentum-resolved single-particle spectral function corresponding to a lattice size of $\sim$ 240 $\times$ 240 with almost negligible finite-size effects.