Superconductivity Driven by Chain Coupling and Electronic Correlations

TL;DR

This paper investigates how weakly coupled Hubbard chains can lead to superconductivity driven by electronic correlations and chain interactions, aligning theoretical predictions with experimental phase diagrams of organic conductors.

Contribution

It combines exact spectral function analysis with renormalization group methods to identify superconductivity as the leading instability in coupled Hubbard chains.

Findings

Superconductivity emerges at low U and doping levels.

Spectral functions reveal a correlation pseudogap.

Predictions match phase diagrams of organic compounds.

Abstract

We present an analysis of a system of weakly coupled Hubbard chains based on combining an exact study of spectral functions of the uncoupled chain system with a renormalization group method for the coupled chains. For low values of the onsite repulsion $U$ and of the doping $\delta$, the leading instability is towards a superconducting state. The process includes excited states above a small correlation pseudogap. Similar features appear in extended Hubbard models in the vicinity of commensurate fillings. Our theoretical predictions are consistent with the phase diagram observed in the (TMTTF)$_2$X and (TMTSF)$_2$X series of organic compounds.