Condensed Matter Physics Seminar: Ian Hays: Progress in Understanding the Superconductivity of UTe2"

The discovery of superconductivity in uranium ditelluride (UTe2) precipitated a flurry of research activity motivated both by strong evidence for triplet pairing as well as an unprecedented slew of distinct superconducting phases as a function of magnetic field and pressure.[1] As usual, a long list of experiments has led to an even longer list of new questions concerning the nature and origin of these different superconducting states, the nature of the magnetic order under pressure, and the presence or absence of magnetic correlations at zero pressure. In this talk I will summarize our current understanding of UTe2, including the overall shape of the P-H phase diagram and our understanding of correlations in the normal state, but I will focus on the effort to determine the superconducting order parameter at low fields and pressures. In this effort, a key role has been played by our measurements of field-angle resolved thermal conductivity below 100mK.[2,3] These experiments have revealed dramatic features as a function of field-angle that indicate the presence of point nodes in the superconducting gap, supporting the hypothesis of triplet pairing and providing a new setting to test old theories of heat transport in superconductors.  

[1] S. Ran, C. Eckberg, Q.-P. Ding, Y. Furukawa, T. Metz, S. R. Saha, I.-L. Liu, M. Zic, H. Kim, J. Paglione, and N. P. Butch, “Nearly ferromagnetic spin-triplet superconductivity” Science 365, 684 (2019).

[2] Ian M. Hayes, Tristin E. Metz, Corey E. Frank, Shanta R. Saha, Nicholas P. Butch, Vivek Mishra, P.J. Hirschfeld, and Johnpierre Paglione, “Robust nodal behavior in the thermal conductivity of superconducting UTe2” Phys. Rev. X. 15 021029 (2025)

[3] Ian M. Hayes, Elliot Fang, Shanta R. Saha, Vivek Mishra, P. J. Hirschfeld, Johnpierre Paglione, “Field-angle-resolved heat transport in UTe2: determination of nodal positions in the superconducting order parameter” arXiv:2512:13877 (2026)

Ian Hayes, Assistan Professor, University of Illinois-Chicago

Host: Venkat Chandrasekhar

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