Identification of the orbital pairing symmetry in UPt₃

This paper summarizes the results of a comprehensive analysis of the thermodynamic and transport data for the superconducting phases of UPt₃. Calculations of the transverse sound attenuation as a function of temperature, frequency, polarization, and disorder are presented for the leading models of the superconducting order parameter. Measurements of the specific heat, thermal conductivity, and transverse sound attenuation place strong constraints on the orbital symmetry of the superconducting order parameter. We show that the superconducting A and B phases are in excellent agreement with pairing states belonging to the odd-parity E_2u orbital representation.