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Possibly—but the new UTe₂ result is not evidence that ordinary, zero-resistance superconductivity continues above its critical temperature. University of Illinois researchers report scanning-tunneling-microscopy signatures they interpret as pair-density-wave (PDW) order persisting after the material’s main superconducting phase disappears. The measurement probes the surface, so it does not establish that the same state exists throughout the bulk.
What the above-transition result means
In a conventional superconductor, Cooper pairs participate in a coherent superconducting phase. A pair-density wave is a proposed state in which the density of pairs varies across space. In the Illinois researchers’ interpretation, PDW-related order can remain after the main superconducting phase is gone.
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The distinction matters: the reported above-transition signal is not proof of unchanged superconductivity above the critical temperature, nor a demonstration of zero electrical resistance there. Instead, the team infers paired order from the behavior of spatially varying electronic modes measured by scanning tunneling microscopy (STM).
How the researchers tested the PDW interpretation
Improved UTe₂ samples and a directional magnetic field
The team studied uranium ditelluride, or UTe₂, using higher-quality crystals grown by a molten-flux method. They used a vector-magnetic-field STM, which let them change temperature and vary both the strength and direction of the magnetic field while measuring the surface electronic spectrum. UTe₂’s anisotropy makes field direction relevant to interpreting its behavior.
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1Repair Windows errors before they cause bigger problems2Scan for outdated or missing drivers - takes under a minute3Clear out junk files and repair common Windows errorsThe researchers tracked spectral modes associated with charge-density-wave (CDW) patterns as those conditions changed. The University of Illinois account reports that the modes’ temperature- and field-dependent responses—including their persistence above the superconducting transition and suppression by magnetic field—matched predictions for PDW order.
Why a charge-density wave alone may not explain the observations
A spatial CDW pattern by itself does not establish a PDW. The researchers argue that a CDW-only explanation conflicts with constraints on how the phases evolve with temperature and magnetic field, while an interpretation that includes intertwined PDW and CDW orders gives a consistent account of the observations. That is the authors’ interpretation of the data, not an uncontested conclusion that all alternative explanations have been ruled out.
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What STM reveals—and what it cannot settle
STM measures electronic properties at a material’s surface. It does not directly photograph individual Cooper pairs; the PDW conclusion is inferred from measured spectral modes and how they respond to experimental conditions.
The researchers acknowledge that UTe₂’s interior could behave differently from its surface. The measurements therefore support a PDW interpretation at the surface but do not, on their own, establish that the same order extends through the bulk. Vidya Madhavan, a co-lead of the project, described the modes’ persistence above the point where superconductivity disappears as a predicted PDW signature that had not been convincingly observed before.
Temperatures and the study to know
The Illinois account says superconductivity in UTe₂ was reported below 2 kelvins. It also labels a Fourier-transform image of surface spatial patterns as measured at 300 millikelvins. That image temperature is not the reported critical temperature.
The study is titled “Evidence of intertwined pair density and charge density wave orders in UTe₂” and was published in Proceedings of the National Academy of Sciences in 2026 (DOI: 10.1073/pnas.2602117123). The university’s account describes the experiment and the researchers’ interpretation: University of Illinois Materials Research Laboratory report.
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