Bandwidth tuning triggers interplay of charge order and superconductivity in two-dimensional organic materials

TL;DR

This study investigates how tuning bandwidth affects the interplay between charge order fluctuations and superconductivity in a two-dimensional organic superconductor, revealing their correlated suppression and providing insights into their relationship.

Contribution

It demonstrates the impact of bandwidth tuning on charge order and superconductivity, combining vibrational spectroscopy, infrared reflectance, and theoretical modeling.

Findings

Charge-order fluctuations are observed and linked to superconductivity.

Reducing effective electronic interactions suppresses both charge order and superconductivity.

Experimental results align with extended Hubbard model calculations.

Abstract

We observe charge-order fluctuations in the quasi-two-dimensional organic superconductor $\beta^{\prime\prime}$-(BEDT-TTF)2 SF5 CH2 CF2 SO3 both by means of vibrational spectroscopy, locally probing the fluctuating charge order, and investigating the in-plane dynamical response by infrared reflectance spectroscopy. The decrease of effective electronic interaction in an isostructural metal suppresses both charge-order fluctuations and superconductivity, pointing on their interplay. We compare the results of our experiments with calculations on the extended Hubbard model.