Reentrant charge order transition in the extended Hubbard model

TL;DR

This paper investigates the extended Hubbard model at quarter filling, revealing a reentrant charge order transition driven by temperature and Coulomb interactions, with significant effects on spectral properties and effective mass.

Contribution

It demonstrates a reentrant charge order transition in the extended Hubbard model using Dynamical Mean Field theory, highlighting the role of temperature and entropy effects.

Findings

Charge ordered phase with different sublattice occupancies at quarter filling.

Effective mass increases sharply at critical Coulomb repulsion V.

Charge ordering transition can be induced by increasing temperature.

Abstract

We study the extended Hubbard model with both on-site and nearest neighbor Coulomb repulsion ($U$ and $V$, respectively) in the Dynamical Mean Field theory. At quarter filling, the model shows a transition to a charge ordered phase with different sublattice occupancies $n_A \nen_B$. The effective mass increases drastically at the critical $V$ and a pseudo-gap opens in the single-particle spectral function for higher values of $V$. The $V_c(T)$-curve has a negative slope for small temperatures, i.e. the charge ordering transition can be driven by increasing the temperature. This is due to the higher spin-entropy of the charge ordered phase.