A phenomenological model of the superconducting state of the Bechgaard salts

TL;DR

This paper uses group theory to analyze the superconducting states of Bechgaard salts, identifying eight symmetry classes and highlighting the polar state as the only one consistent with experimental data.

Contribution

It provides a comprehensive symmetry classification of superconducting states in Bechgaard salts and identifies the polar state as the experimentally consistent phase.

Findings

Eight symmetry distinct superconducting states identified

Only the fully gapped polar state matches experimental observations

The polar state's gap function is of the form d(k) = psi_uk,0,0

Abstract

We present a group theoretical analysis of the superconducting state of the Bechgaard salts, e.g., (TMTSF)_2PF_6 or (TMTSF)_2ClO_6. We show that there are eight symmetry distinct superconducting states. Of these only the (fully gapped, even frequency, p-wave, triplet) 'polar state' is consistent with the full range of the experiments on the Bechgaard salts. The gap of the polar state is d(k) (psi_uk,0,0), where psi_uk may be any odd parity function that is translationally invariant.