# Field-induced carrier delocalization in the strain-induced Mott insulating state of an organic superconductor

## TL;DR

This study investigates how an electric field influences carrier behavior in a strain-induced Mott insulator of an organic superconductor, revealing field-induced delocalization of carriers and changes in conductivity and mobility.

## Contribution

It demonstrates that gate voltage can delocalize carriers in a Mott insulator, altering its electronic properties, which is a novel insight into field effects in correlated electron systems.

## Key findings

- Conductivity follows activated transport with gate-dependent activation energy.
- Effective mobility of hole carriers increases with positive gate voltage.
- Carrier delocalization is driven by the electric field, not just doping.

## Abstract

We report the influence of the field effect on the dc resistance and Hall coefficient in the strain-induced Mott insulating state of an organic superconductor $\kappa$-(BEDT-TTF)$_{2}$Cu[N(CN)$_{2}$]Br. Conductivity obeys the formula for activated transport $\sigma_{\Box} = \sigma_{0}\exp(-W/k_{B}T)$, where $\sigma_{0}$ is a constant and $W$ depends on the gate voltage. The gate voltage dependence of the Hall coefficient shows that, unlike in conventional FETs, the effective mobility of dense hole carriers ($\sim1.6\times 10^{14}$ cm$^{-2}$) is enhanced by a positive gate voltage. This implies that carrier doping involves delocalization of intrinsic carriers that were initially localized due to electron correlation.