Finite-Temperature Properties across the Charge Ordering Transition -- Combined Bosonization, Renormalization Group, and Numerical Methods

TL;DR

This paper combines analytical and numerical methods to study the finite-temperature charge ordering transition in a quasi-one-dimensional extended Hubbard model, revealing how physical properties like susceptibility and resistivity change across the transition.

Contribution

It introduces a novel theoretical scheme combining bosonization, renormalization group, and numerical simulations to analyze finite-temperature properties of charge ordering transitions.

Findings

Spin susceptibility does not show a steep singularity at T_CO.

Resistivity exhibits a sudden increase at T_CO.

Characteristic temperature dependence observed below T_CO.

Abstract

We theoretically describe the charge ordering (CO) metal-insulator transition based on a quasi-one-dimensional extended Hubbard model, and investigate the finite temperature ($T$) properties across the transition temperature, $T_{\rm CO}$. In order to calculate $T$ dependence of physical quantities such as the spin susceptibility and the electrical resistivity, both above and below $T_{\rm CO}$, a theoretical scheme is developed which combines analytical methods with numerical calculations. We take advantage of the renormalization group equations derived from the effective bosonized Hamiltonian, where Lanczos exact diagonalization data are chosen as initial parameters, while the CO order parameter at finite-$T$ is determined by quantum Monte Carlo simulations. The results show that the spin susceptibility does not show a steep singularity at $T_{\rm CO}$, and it slightly increases compared to the case without CO because of the suppression of the spin velocity. In contrast, the resistivity exhibits a sudden increase at $T_{\rm CO}$, below which a characteristic $T$ dependence is observed. We also compare our results with experiments on molecular conductors as well as transition metal oxides showing CO.