Heat transport and the nature of the order parameter in superconductingUPt3

Abstract

Recent thermal conductivity data on the heavy fermion superconductor ${\mathrm{UPt}}_3$ have been interpreted as offering support for an ${\mathit{E}}_{2\mathit{u}}$ model of the order parameter as opposed to an ${\mathit{E}}_{1\mathit{g}}$ 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. © 1996 The American Physical Society.