Multiphase superconductivity in PdBi<sub>2</sub>.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39746941.
- Also identified by DOI 10.1038/s41467-024-54867-x and PMC identifier 11696495.
- 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
Unconventional superconductivity, where electron pairing does not involve electron-phonon interactions, is often attributed to magnetic correlations in a material. Well known examples include high-T<sub>c</sub> cuprates and uranium-based heavy fermion superconductors. Less explored are unconventional superconductors with strong spin-orbit coupling, where interactions between spin-polarised electrons and external magnetic field can result in multiple superconducting phases and field-induced transitions between them, a rare phenomenon in the superconducting state. Here we report a magnetic-field driven phase transition in β-PdBi<sub>2</sub>, a layered non-magnetic superconductor. Our tunnelling spectroscopy on thin PdBi<sub>2</sub> monocrystals incorporated in planar superconductor-insulator-normal metal junctions reveals a marked discontinuity in the superconducting properties with increasing in-plane field, which is consistent with a transition from conventional (s-wave) to nodal pairing. Our theoretical analysis suggests that this phase transition may arise from spin polarisation and spin-momentum locking caused by locally broken inversion symmetry, with p-wave pairing becoming energetically favourable in high fields. Our findings also reconcile earlier predictions of unconventional multigap superconductivity in β-PdBi<sub>2</sub> with previous experiments where only a single s-wave gap could be detected.