Effect of electronic correlations on the metal-insulator transition of $\alpha$-(BEDT-TTF)$_2$I$_3$: theoretical and experimental investigations of its optical properties

TL;DR

This paper investigates how electronic correlations influence the metal-insulator transition in the organic salt $ ext{α}$(BEDT-TTF)$_2$I$_3$, combining experimental optical measurements with first-principles calculations.

Contribution

It provides a combined theoretical and experimental analysis of the role of electronic correlations in the metal-insulator transition of $ ext{α}$(BEDT-TTF)$_2$I$_3$, highlighting the impact on optical properties.

Findings

Optical properties are well described by DFT calculations.

Electronic correlations significantly affect the metal-insulator transition.

Charge ordering occurs at $T_{CO}=135$ K.

Abstract

The organic salt $\alpha$-(BEDT-TTF)$_2$I$_3$ is considered a model system for metal-insulator transition due to electronic charge ordering at $T_{\rm CO}=135$~K. The optical properties obtained from polarized reflection measurements above and below $T_{\rm CO}$ can be well described by calculations based on first-principle density-functional theory (DFT). We discuss the effect of electronic correlations on the metal-insulator transition.