Radial Line Nodes in Weakly Anisotropic Noncentrosymmetric Superconductors

TL;DR

This paper investigates radial line nodes in weakly anisotropic noncentrosymmetric superconductors, revealing their controllability, unique low-temperature behavior, and how Andreev conductance experiments can identify them.

Contribution

It introduces the concept of radial line nodes in weakly anisotropic NCSs and analyzes their topology, controllability, and experimental detection methods.

Findings

RLNs depend on chemical potential and IS breaking degree

RLNs cause intermediate low-temperature behavior in energy gap

Andreev conductance experiments can identify RLNs

Abstract

Noncentrosymmetric superconductors (NCSs) without inversion symmetry (IS) have a doublet of mixed parity order parameters (OPs) which can have nodes. In addition to the angular line nodes (ALNs) existing under strong anisotropy, radial line nodes (RLNs) exist in weakly anisotropic NCSs due to the radial momentum dependence of the interactions and the broken IS. We study the topology, the number and the positions of RLNs which can be controlled by the chemical potential and the degree of IS breaking. The RLNs exhibit a low temperature behaviour intermediate between exponential suppression and the integer powerlaw. For this reason they are difficult to detect and may be inadvertently missed in a number of experiments. We show that Andreev conductance experiments can efficiently distinguish RLNs in the energy gap from the other fundamental nodes.