Spin-Triplet Superconductivity Mediated by Phonons in Quasi-One-Dimensional Systems

TL;DR

This paper demonstrates that phonon-mediated spin-triplet superconductivity can occur in quasi-one-dimensional systems with open Fermi surfaces, highlighting the importance of system-specific features and interactions.

Contribution

It reveals that phonons alone can induce spin-triplet pairing in Q1D systems, emphasizing the role of open Fermi surfaces and interaction parameters in pairing symmetry.

Findings

Nodeless spin-triplet state is more favorable in (TMTSF)_2X.

Spin-triplet superconductivity occurs under weak screening and strong Coulomb interaction.

Open Fermi surface is crucial for pairing symmetry in Q1D systems.

Abstract

We investigate the spin-triplet superconductivity mediated by phonons in quasi-one-dimensional (Q1D) systems with open Fermi surfaces. We obtain the ground state phase diagrams. It is found that spin-triplet superconductivity occurs for weak screening and strong on-site Coulomb interaction, even in the absence of any additional nonphonon pairing interactions. We find that the nodeless spin-triplet state is more favorable than the spin-triplet state with line nodes, for the parameter values of the Q1D superconductors (TMTSF)_2X. We also find that Q1D open Fermi surface, which is the specific feature of this system, plays an essential role in the pairing symmetry. We discuss the compatibility of the present results with the experimental results in these compounds.