Ring Exchange Mechanism for Triplet Superconductivity in a Two-Chain Hubbard Model: Possible Relevance to Bechgaard Salts

TL;DR

This paper demonstrates that a ring exchange mechanism in a two-chain Hubbard model can induce triplet superconductivity, potentially explaining superconductivity observed in Bechgaard salts.

Contribution

It introduces a novel ring exchange mechanism that promotes triplet pairing in a two-chain Hubbard model, linking microscopic interactions to superconductivity in organic salts.

Findings

Ring exchange induces ferromagnetic correlations.

Attractive interaction and long-range triplet pairing observed.

Possible relevance to Bechgaard salts' superconductivity.

Abstract

The density-matrix renormalization group method is used to study the ground state of the two-chain zigzag-bond Hubbard model at quarter filling. We show that, with a proper choice of the signs of hopping integrals, the ring exchange mechanism yields ferromagnetic spin correlations between interchain neighboring sites, and produces the attractive interaction between electrons as well as the long-range pair correlations in the spin-triplet channel, thereby leading the system to triplet superconductivity. We argue that this novel mechanism may have possible relevance to observed superconductivity in Bechgaard salts.