Giant transverse magnetic fluctuations at the edge of re-entrant superconductivity in UTe<sub>2</sub>.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 42056086.
- Also identified by DOI 10.1038/s41467-026-71899-7 and PMC identifier 13128824.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
UTe<sub>2</sub> exhibits the remarkable phenomenon of re-entrant superconductivity, whereby the zero-resistance state reappears above 40 tesla after being suppressed with a field of around 10 tesla. One potential pairing mechanism, invoked in the related re-entrant superconductors UCoGe and URhGe, involves transverse fluctuations of a ferromagnetic order parameter. However, the requisite ferromagnetic order-present in both UCoGe and URhGe-is absent in UTe<sub>2</sub>, and neutron scattering shows instead that the magnetic susceptibility is peaked at an antiferromagnetic wavevector. Here, we measure the magnetotropic susceptibility of UTe<sub>2</sub> across two field-angle planes. This quantity is sensitive to the magnetic susceptibility in a direction transverse to the applied magnetic field-a quantity that is not accessed in conventional magnetization measurements. We observe a very large decrease in the magnetotropic susceptibility over a broad range of field orientations, indicating a large increase in the transverse magnetic susceptibility. Because our technique probes the magnetic susceptibility in the long wavelength (q = 0) limit, this suggests that the strong transverse susceptibility arises from ferromagnetic spin fluctuations. These ferromagnetic fluctuations are likely important for understanding the pairing mechanism in UTe<sub>2</sub>, as all three superconducting phases of UTe<sub>2</sub> surround this region of enhanced susceptibility in the field-angle phase diagram.