# Metal-Insulator Transition in the Dimerized Organic Conductor $\kappa$-(BEDT-TTF)$_2$Hg(SCN)$_2$Br

## TL;DR

This study investigates the metal-insulator transition in the organic conductor $$-(BEDT-TTF)$_2$Hg(SCN)$_2$Br through transport, dielectric, and optical measurements, comparing it with similar salts to understand the transition's nature.

## Contribution

It provides comprehensive experimental analysis of the metal-insulator transition in a specific organic conductor and compares it with related compounds to elucidate underlying mechanisms.

## Key findings

- Transition occurs below 80 K with a large increase in resistivity.
- Comparison with $$-analogue reveals differences in charge-order behavior.
- Experimental data suggest a complex interplay of electronic correlations.

## Abstract

The organic charge-transfer salt $\kappa$-(BEDT-TTF)$_{2}$Hg(SCN)$_{2}$Br is a quasi two-dimensional metal with a half-filled conduction band at ambient conditions. When cooled below $T=80$ K it undergoes a pronounced transition to an insulating phase where the resistivity increases many orders of magnitude. In order to elucidate the nature of this metal-insulator transition we have performed comprehensive transport, dielectric and optical investigations. The findings are compared with other dimerized $\kappa$-(BEDT-TTF) salts, in particular the Cl-analogue, where a charge-order transition takes place at $T_{\rm CO}=30$ K.