Finite-temperature investigation of quarter filled ladder systems

TL;DR

This study uses determinantal Quantum Monte Carlo to explore charge ordering in quarter-filled ladder systems at finite temperature, revealing a crossover behavior, exponential correlation length growth, and a single-particle gap.

Contribution

It provides the first finite-temperature analysis of charge order in quarter-filled ladders, highlighting the role of Coulomb repulsion and temperature effects.

Findings

Charge order parameter shows a crossover with temperature.

Correlation length grows exponentially with inverse temperature.

A single-particle gap is observed at high Coulomb repulsion.

Abstract

We investigate charge ordering in a quarter-filled ladder at finite temperature by determinantal Quantum Monte Carlo. The sign problem is moderate in a wide range of model parameters relevant for NaV2O5. The charge order parameter exhibits a crossover as a function of inverse temperature on finite systems. Above a critical nearest neighbor Coulomb repulsion, the correlation length grows exponentially with inverse temperature, indicative of the ordered phase at T=0. We find a clear single-particle gap manifesting itself in a flat n(\mu) dependence at large nearest neighbor Coulomb repulsion.