Interplay between the charge density wave phase and a pseudogap under antiferromagnetic correlations

TL;DR

This paper investigates how short-range antiferromagnetic correlations affect the charge density wave phase and pseudogap formation in a strongly correlated electron system using a Hubbard model and BCS-like approach.

Contribution

It introduces a combined theoretical framework to analyze the influence of antiferromagnetic correlations on CDW and pseudogap phenomena in correlated materials.

Findings

Antiferromagnetic correlations significantly modify the Fermi surface within the CDW phase.

A Lifshitz transition occurs inside both the CDW phase and the normal state.

The pseudogap appears in the band structure and density of states, influenced by Coulomb interaction.

Abstract

In this study, we explore the impact of short-range antiferromagnetic correlations on the charge density wave (CDW) phase in strongly correlated electron systems exhibiting the pseudogap phenomenon. Our investigation employs a n-pole approximation to consider the repulsive Coulomb interaction $(U)$ and antiferromagnetic correlations. Utilizing a two-dimensional Hubbard model for the Coulomb interaction and a BCS-like model for the CDW order parameter, we observe that an increase in $U$ enhances antiferromagnetic fluctuations, resulting in a flattened re-normalized band around the anti-nodal point $(\pi,0)$. The pseudogap manifests in the band structure and density of states, prompting an exploration across various $U$ and occupation number values. Our findings indicate that antiferromagnetic correlations significantly influence the CDW state, as the Fermi surface is reconstructed within the ordered phase. Furthermore, we find a Lifhsitz transition inside both the CDW phase and the normal state, with the latter preceding the onset of the pseudogap.