Multigap Superconductivity in the Ferromagnetic Superconductor UCoGe Revealed by Thermal Conductivity Measurements

TL;DR

This study reveals multigap superconductivity in UCoGe, a ferromagnetic superconductor, through thermal conductivity measurements showing distinct temperature dependencies and a plateau in field response, indicating complex gap structure.

Contribution

First experimental evidence of multigap superconductivity in UCoGe using thermal conductivity measurements under magnetic fields.

Findings

Thermal conductivity shows linear and quadratic temperature dependencies at different fields.

A plateau in residual thermal conductivity appears at magnetic fields above 1 Tesla.

Results suggest the presence of a line of nodes in the superconducting gap.

Abstract

We performed thermal conductivity measurements on a single crystal of the ferromagnetic superconductorUCoGe under magnetic field. Two different temperature dependencies of the thermal conductivity are observed, for H//b linear at low magnetic field and quadratic for magnetic field larger than 1 Tesla. At the same field value, a plateau appears in the field dependency of the residual term of thermal conductivity. Such observations suggest a multigap superconductivity with a line of nodes in the superconducting gap.