Heat Transport and the Nature of the Order Parameter in Superconducting $UPt_3$

TL;DR

This paper analyzes thermal conductivity data in UPt3 to evaluate different models of its superconducting order parameter, emphasizing the importance of Fermi surface effects and the need for further experimental data.

Contribution

It provides a theoretical analysis of the thermal conductivity data considering Fermi surface and gap anisotropy, clarifying the limitations of current experimental distinctions between models.

Findings

Current data constrain gap anisotropy but do not definitively distinguish models.

Fermi surface effects significantly influence thermal conductivity interpretations.

Further measurements on samples of varying quality are necessary.

Abstract

Recent thermal conductivity data on the heavy fermion superconductor $UPt_3$ have been interpreted as offering support for an $E_{2u}$ model of the order parameter as opposed to an $E_{1g}$ model. In this paper, we analyze this issue from a theoretical standpoint including the detailed effects of Fermi surface and gap anisotropy. Our conclusion is that although current data put strong constraints on the gap anisotropy, they cannot definitively distinguish between these two models. Measurements on samples of varying quality could be decisive in this regard, however.