Transport criticality of the first-order Mott transition in a quasi-two-dimensional organic conductor, $\kappa$-(BEDT-TTF)$_{2}$Cu[N(CN)$_{2}$]Cl

TL;DR

This study experimentally investigates the first-order Mott transition in a quasi-two-dimensional organic insulator using resistance measurements under pressure, revealing critical behavior consistent with theoretical predictions and liquid-gas transition analogy.

Contribution

It provides experimental evidence of the Mott transition criticality and its critical endpoint, supporting dynamical mean field theory predictions.

Findings

Demonstrated a clear resistance jump indicating a first-order Mott transition.

Identified a critical endpoint at 38 K with divergence in pressure derivative of resistance.

Established phenomenological similarity between Mott transition and liquid-gas transition.

Abstract

An organic Mott insulator, $\kappa$-(BEDT-TTF)$_{2}$Cu[N(CN)$_{2}$]Cl, was investigated by resistance measurements under continuously controllable He gas pressure. The first-order Mott transition was demonstrated by observation of clear jump in the resistance variation against pressure. Its critical endpoint at 38 K is featured by vanishing of the resistive jump and critical divergence in pressure derivative of resistance, $|\frac{1}{R}\frac{\partial R}{\partial P}|$, which are consistent with the prediction of the dynamical mean field theory and have phenomenological correspondence with the liquid-gas transition. The present results provide the experimental basis for physics of the Mott transition criticality.