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What causes the variation in superconducting properties of UTe2?

Journal Article · · Journal of Magnetism and Magnetic Materials
Reaching a consensus on the superconducting order parameter of unconventional superconductors remains a central challenge in the field of magnetically-mediated superconductivity. Though UTe2 is largely accepted as a rare example of an odd-parity superconductor, its precise order parameter remains highly debated, even at ambient conditions. A key underlying issue is the large sample-to-sample variation in superconducting properties at zero applied pressure and magnetic field. Here, we investigate the origin of the observed variation by means of single crystal x-ray diffraction (SC-XRD) and scanning transmission electron microscopy (STEM) measurements. Our results reveal highly ordered crystalline lattices, in agreement with the expected Immm structure, and no signs of uranium vacancies. Tiny amounts of interstitial defects, however, are observed on the Te2 layers that host Te chains along the b axis. We argue that these defects give rise to slightly enhanced atomic displacement parameters observed in SC-XRD data and are enough to disrupt the unconventional superconducting state in UTe2. Our findings highlight the need to focus future order parameter determination efforts on single crystals of UTe2 with minimal amounts of structural disorder.
Research Organization:
Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
Sponsoring Organization:
National Science Foundation (NSF); USDOE Laboratory Directed Research and Development (LDRD) Program; USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division (MSE)
Grant/Contract Number:
89233218CNA000001
OSTI ID:
3003179
Report Number(s):
LA-UR--25-28729; 10.1016/j.jmmm.2025.173650
Journal Information:
Journal of Magnetism and Magnetic Materials, Journal Name: Journal of Magnetism and Magnetic Materials Vol. 636; ISSN 0304-8853
Publisher:
ElsevierCopyright Statement
Country of Publication:
United States
Language:
English

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