Electron localization near Mott transition in organic superconductor $\kappa$-(BEDT-TTF)$_{2}$Cu[N(CN)$_{2}]$Br

TL;DR

This study investigates how disorder from X-ray irradiation induces electron localization in an organic superconductor near the Mott transition, revealing enhanced localization due to Coulomb interactions affecting low-temperature conduction.

Contribution

It provides experimental evidence of disorder-induced electron localization and Coulomb interaction effects near the Mott transition in an organic superconductor.

Findings

X-ray irradiation causes Anderson-type localization.

Resistivity shows variable range hopping conduction.

Electron localization is enhanced by Coulomb interactions.

Abstract

The effect of disorder on the electronic properties near the Mott transition is studied in an organic superconductor $\kappa$-(BEDT-TTF)$_{2}$Cu[N(CN)$_{2}$]Br, which is systematically irradiated by X-ray. We observe that X-ray irradiation causes Anderson-type electron localization due to molecular disorder. The resistivity at low temperatures demonstrates variable range hopping conduction with Coulomb interaction. The experimental results show clearly that the electron localization by disorder is enhanced by the Coulomb interaction near the Mott transition.