Gap nodes in the superconducting phase of the itinerant ferromagnet $UGe_2$

TL;DR

This paper analyzes the symmetry-allowed superconducting gap structures in UGe₂, identifying the presence of symmetry-required gap nodes and discussing their implications for experimental detection.

Contribution

It determines the possible superconducting phases in UGe₂ considering strong spin-orbit coupling and identifies the symmetry-enforced gap nodes in these phases.

Findings

Identified symmetry-allowed superconducting phases in UGe₂.

Found that certain phases necessarily have gap nodes due to symmetry.

Discussed experimental signatures of the gap nodes.

Abstract

For the UGe$_2$ ferromagnetic superconductor the forms of the order parameter admitted by the crystal symmetry within the strong spin-orbit coupling scheme are written down. For each of the two possible phases existence of gap nodes required by symmetry is discussed and the nodes are found. Some consequences of presence of the nodes, which may be useful for experimental identification of the phases are discussed as well.