Upper critical field of p-wave superconductors with orthorhombic symmetry

TL;DR

This paper extends the Scharnberg-Klemm theory to analyze the upper critical field in orthorhombic p-wave superconductors with broken symmetry, explaining experimental behaviors in ferromagnetic superconductor UCoGe.

Contribution

It introduces a generalized model for $H_{c2}$ in orthorhombic p-wave superconductors with partial symmetry breaking, applicable to materials like UCoGe.

Findings

$H_{c2}$ can show upward curvature in all crystal axes.

The model fits low-field UCoGe data well.

Provides insights into the effects of symmetry breaking on superconducting properties.

Abstract

We extend the Scharnberg-klemm theory of $H_{c2}$ in p-wave superconductors with broken symmetry to cases of partially broken symmetry in an orthorhombic crystal, as is appropriate for the more exotic ferromagnetic superconductor UCoGe in strong applied magnetic fields. For some partially broken symmetry cases, $H_{c2}$ can mimic upward curvature in all three crystal axis directions, and reasonably good fits to some of the the low-field UCoGe data are obtained.