CMT69

Thermal Conductivity of UPt₃ at Low Temperatures

Abstract:
We study the thermal conductivity within the E_1g and E_2u 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/T_c > 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 E_1g or E_2u 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 E_1g and E_2u 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, lim_{T → 0} κ_c/T, is universal for the E_2u model, but non-universal for the E_1g model. Thus, impurity concentration studies at very low temperatures should differentiate between the nodal structures of the E_2u and E_1g models.

Paper: [PDF] [arXiv]

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