Simultaneous Control of Bandfilling and Bandwidth in Electric Double-Layer Transistor Based on Organic Mott Insulator $\kappa$-(BEDT-TTF)$_{2}$Cu[N(CN)$_{2}$]Cl

TL;DR

This paper discusses a tunable organic Mott insulator-based electric double-layer transistor that enables control over bandfilling and bandwidth, revealing superconductivity and non-Fermi liquid behaviors near the Mott transition.

Contribution

It introduces a novel organic Mott insulator transistor platform with simultaneous control of bandfilling and bandwidth, and explores its electronic phases and doping asymmetries.

Findings

Superconductivity observed with nearly identical transition temperatures for electron and hole doping.

Normal state exhibits non-Fermi liquid behaviors under electric double-layer doping.

Model calculations explain doping asymmetry emphasizing the role of the noninteracting band structure.

Abstract

The physics of quantum many-body systems have been studied using bulk correlated materials, and recently, moir\'e superlattices formed by atomic bilayers have appeared as a novel platform in which the carrier concentration and the band structures are highly tunable. In this brief review, we introduce an intermediate platform between those systems, namely, a band-filling- and bandwidth-tunable electric double-layer transistor based on a real organic Mott insulator $\kappa$-(BEDT-TTF)$_{2}$Cu[N(CN)$_{2}$]Cl. In the proximity of the bandwidth-control Mott transition at half filling, both electron and hole doping induced superconductivity (with almost identical transition temperatures) in the same sample. The normal state under electric double-layer doping exhibited non-Fermi liquid behaviors as in many correlated materials. The doping levels for the superconductivity and the non-Fermi liquid behaviors were highly doping-asymmetric. Model calculations based on the anisotropic triangular lattice explained many phenomena and the doping asymmetry, implying the importance of the noninteracting band structure (particularly the flat part of the band).