We study the thermal conductivity within the E1g and E2u models for superconductivity in UPt3 and compare the theoretical results for electronic heat transport with recently measured results reported by Lussier, Ellman and Taillefer. The existing data down to T/Tc > 0.1 provides convincing evidence for the presence of both line and point nodes in the gap, but the data can be accounted for either by an E1g or E2u order parameter. We discuss the features of the pairing symmetry, Fermi surface, and excitation spectrum that are reflected in the thermal conductivity at very low temperatures. Significant differences between the E1g and E2u models are predicted to develop at excitation energies below the bandwidth of the impurity-induced Andreev bound states. The zero-temperature limit of the c-axis thermal conductivity, limT → 0 κc/T, is universal for the E2u model, but non-universal for the E1g model. Thus, impurity concentration studies at very low temperatures should differentiate between the nodal structures of the E2u and E1g models.
Paper: [PDF] [arXiv]