A topological superconductor tuned by electronic correlations.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 41449175.
- Also identified by DOI 10.1038/s41467-025-67957-1 and PMC identifier 12858962.
- Licence recorded as CC BY-NC-ND.
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Abstract
A topological superconductor, characterized by either a chiral order parameter or a topological surface state in proximity to bulk superconductivity, is foundational to topological quantum computing. A key open challenge is whether electron-electron interactions can tune such topological superconducting phases. Here, we provide experimental signatures of a unique topological superconducting phase in competition with electronic correlations in 10-unit-cell thick FeTe<sub>x</sub>Se<sub>1-x</sub> films grown on SrTiO<sub>3</sub> substrates. When the Te content x exceeds 0.7, we observe a topological transition marked by the emergence of a superconducting surface state. Near the FeTe limit, the system undergoes another transition where the surface state disappears, and superconductivity is suppressed. Theory suggests that electron-electron interactions in the odd-parity xy<sup>-</sup> band drives this second topological transition. The flattening and eventual decoherence of d<sub>xy</sub>-derived bands track the superconducting dome, linking correlation effects directly to superconducting coherent transport. Our work establishes many-body electronic correlations as a sensitive knob for tuning topology and superconductivity, offering a pathway to engineer new topological phases in correlated materials.