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Symmetry properties of the order parameter are among the most fundamental characteristics of a superconductor. UTe2, which was found to feature an exceedingly large upper critical field and striking reentrant behavior at low temperatures, is widely believed to possess a spin-triplet pairing symmetry. However, unambiguous evidence for such a pairing symmetry is still lacking, especially at zero and low magnetic fields. The presence of an inversion crystalline symmetry in UTe2requires that, if it is indeed a spin-triplet superconductor, the order parameter must be of odd parity. We report here phase-sensitive measurements of the symmetry of the orbital part of the order parameter using the Josephson effect. The selection rule in the orientation dependence of the Josephson coupling between In, ans-wave superconductor, and UTe2suggests strongly that UTe2possesses the odd-parity pairing state of B1usymmetry near zero magnetic field, making it a spin-triplet superconductor. We also report the apparent formation of Andreev surface bound states on the (1−10) surface of UTe2.
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This content will become publicly available on May 29, 2026
Pair wave function symmetry in UTe 2 from zero-energy surface state visualization
Although nodal spin-triplet topological superconductivity appears probable in uranium ditelluride (UTe2), its superconductive order parameter Δkremains unestablished. In theory, a distinctive identifier would be the existence of a superconductive topological surface band, which could facilitate zero-energy Andreev tunneling to an s-wave superconductor and also distinguish a chiral from a nonchiral Δkthrough enhanced s-wave proximity. In this study, we used s-wave superconductive scan tips and detected intense zero-energy Andreev conductance at the UTe2(0-11) termination surface. Imaging revealed subgap quasiparticle scattering interference signatures witha-axis orientation. The observed zero-energy Andreev peak splitting with enhanced s-wave proximity signifies that Δkof UTe2is a nonchiral state:B1u,B2u, orB3u. However, if the quasiparticle scattering along theaaxis is internodal, then a nonchiralB3ustate is the most consistent for UTe2.
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- Award ID(s):
- 2201516
- PAR ID:
- 10600014
- Publisher / Repository:
- Science
- Date Published:
- Journal Name:
- Science
- Volume:
- 388
- Issue:
- 6750
- ISSN:
- 0036-8075
- Page Range / eLocation ID:
- 938 to 944
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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