Theory of thermal conductivity in UTe₂

The superconducting state of the heavy-fermion metal UTe2 has attracted considerable interest because of evidence for spin-triplet Cooper pairing, including remarkable resilient behavior in high magnetic fields and potential non-trivial topology. Progress on the nature of superconductivity in this fascinating system would be greatly assisted by proper identification of the superconducting order parameter in the low-field phase, particularly its nodal structure. Here I review thermal conductivity experiments[1] on UTe2 with a magnetic field rotating in the bc plane perpendicular to the heat current. The theory of triplet state thermal conductivity[2] including disorder- and spin-fluctuation limited electronic thermal conductivity is used to understand recent data of Hayes et al. and extract information about the location of nodes of the order parameter. We analyze the data in terms of a realistic Fermi surface of U and Te states and order parameters with symmetries based on nearest- and next-nearest-neighbor U pairing.

[1] Ian M. Hayes, Tristin E. Metz, Corey E. Frank, Shanta R. Saha, Nicholas P. Butch, Vivek Mishra, P. J. Hirschfeld, Johnpierre Paglione, Phys Rev. X 15, 021029 (2025).

[2] V. Mishra, G. Wang, and P. J. Hirschfeld, Front. Phys. 12,1397524 (2024).