Charge order on a triangular lattice with Mott physics and arbitrary charge density

TL;DR

This paper investigates charge ordering on a triangular lattice using the extended Hubbard model with DMFT, revealing a complex phase diagram with various phases, transitions, and asymmetries, enhanced by mean-field insights.

Contribution

It provides a detailed phase diagram of charge order phenomena on a triangular lattice considering Mott physics and arbitrary charge density, highlighting new phases and transition behaviors.

Findings

Identification of pinball-liquid phases with different driving mechanisms

Discovery of phase transitions changing order with model parameters

Observation of a small intermediate metallic phase on the electron-doped side

Abstract

Triangular-lattice systems attract a lot of attention due to various frustration-induced and strongly correlated effects. Here, we focus on the charge-ordering phenomenon by means of investigation of the extended Hubbard model with dynamical mean-field theory (DMFT). By considering the intersite nearest-neighbor interaction we have found a very rich phase diagram that contains large number of features, phases, and phase transitions. Among them are pinball-liquid (PL) phases where we distinguish charge-transfer-driven and Mott-localization-driven PLs; phase transitions that change their order as model parameters evolve (from discontinuous to continuous); very strong particle-hole asymmetry. Various features of the phase diagram are found to be better understood by means of the simple mean-field approximation (MFA). Moreover, besides helping with interpretation of the phase diagram, the MFA results together with results for the atomic-limit model are found to be able to set rather good expectations on how the DMFT phase diagram should look like. Nevertheless, a few features were not expected and are found within the DMFT, such as a small-region intermediate metallic phase on an electron-doped side of the phase diagram.