Nodeless d-wave superconductivity in a quasi-one-dimensional organic superconductor under anion order

TL;DR

This paper proposes a mechanism for nodeless d-wave superconductivity in a quasi-one-dimensional organic superconductor caused by anion order, explaining experimental observations of thermal conductivity and NMR relaxation.

Contribution

It introduces a novel mechanism where anion order splits Fermi surfaces, removing nodes in the d-wave gap and creating a small energy gap in the superconductor.

Findings

Fermi surface splitting eliminates d-wave line nodes.

A small energy gap explains thermal conductivity behavior.

NMR relaxation rate data is consistent with the model.

Abstract

We propose a mechanism of nodeless d-wave superconductivity in a quasi-one-dimensional organic superconductor under anion order. It is shown that split of the Fermi surfaces due to the anion order eliminates the line nodes of a d-wave gap function on the Fermi surfaces, and a small finite energy gap appears in the quasi-particle excitations of superconductivity. We discuss that temperature dependences of thermal conductivity and NMR relaxation rate observed in a quasi-one-dimensional organic superconductor (TMTSF)2ClO4 can be explained consistently by the small energy gap.