SO(4) Theory of Competition between Triplet Superconductivity and Antiferromagnetism in Bechgaard Salts

TL;DR

This paper explores the competition and coexistence of antiferromagnetism and triplet superconductivity in Bechgaard salts using an SO(4) symmetric framework, explaining experimental observations and predicting neutron scattering features.

Contribution

It introduces an SO(4) symmetric theory unifying antiferromagnetism and triplet superconductivity in quasi-1D systems, applicable to Bechgaard salts.

Findings

SO(4) symmetry constrains the phase diagram.

Coexistence of antiferromagnetic and superconducting phases.

Prediction of a neutron scattering resonance in superconducting samples.

Abstract

Motivated by recent experiments with Bechgaard salts, we investigate the competition between antiferromagnetism and triplet superconductivity in quasi one-dimensional electron systems. We unify the two orders in an SO(4) symmetric framework, and demonstrate the existence of such symmetry in one-dimensional Luttinger liquids. SO(4) symmetry, which strongly constrains the phase diagram, can explain coexistence regions between antiferromagnetic, superconducting, and normal phases, as observed in (TMTSF)$_2$PF$_6$. We predict a sharp neutron scattering resonance in superconducting samples.