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 FeTexSe1-x films grown on SrTiO3 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− band drives this second topological transition. The flattening and eventual decoherence of dxy-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.
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Acknowledgements
We thank Zhi-Xun Shen, Rafael Fernandes, Peter Littlewood, and David Awschalom for helpful discussions. MBE and ARPES measurements were supported by NSF via Grant No. DMR-2145373 (S.Y.). Transport measurements were done at facilities supported by NSF via Grant No. DMR-2011854 (S.Y.). Fabrication of electrical contacts for transport measurements was supported by NSF via Grant CMMI-2240489 (S.Y.). S.M. and C.L.J. acknowledge the support from the Air Force Office of Scientific Research by the Department of Defense under Award No. FA9550-23-1-0498 (S.M.) of the DEPSCoR program. S.M. and C.L.J. benefited from the Frontera supercomputer at the Texas Advanced Computing Center (TACC) at The University of Texas at Austin, which is supported by National Science Foundation Grant No. OAC-1818253 (S.M.). S.M. also acknowledges the support from NSF OAC-2311558 (S.M.). STEM measurements were supported by the Air Force Office of Scientific Research under award number FA9550-20-1-0302 (P.Y.H.). STEM measurements were carried out in part in the Materials Research Laboratory Central Facilities at the University of Illinois at Urbana-Champaign. ICP-MS measurements were supported by the U.S. DOE Basic Energy Sciences under Grant No. DE-SC0023317 (C.L. and S.Y.). X.W. acknowledges support from the National Key R&D Program of China (Grant No. 2023YFA1407300) (X.W.) and the National Natural Science Foundation of China (Grant No. 12447103) (X.W.). STM measurements performed at the Center for Nanoscale Materials, a U.S. Department of Energy Office of Science User Facility, was supported by the U.S. DOE, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357 (N.P.G.).
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H.L., C.Y., and S.Y. conceived and designed the experiment. H.L. and C.Y. grew the thin films and performed the ARPES experiments with assistance from Q.G., G.B., K.D.N., and Y.B. H.L., P.S., and Y.B. performed the electrical transport measurements. G.M.N. and P.Y.H. performed the STEM measurement. N.P.G., C.Y. and H.L. performed the STM measurement. C.J. and S.M. performed the DFT+eDMFT calculation. X.W. and C.-X.L. performed the tight-binding calculation. G.Y., S.C., and C.L. performed the ICP-MS measurements. H.L. and S.Y. analyzed and interpreted the experimental data. All authors participated in discussions and in writing of the manuscript.
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Lin, H., Jacobs, C.L., Yan, C. et al. A topological superconductor tuned by electronic correlations. Nat Commun (2025). https://doi.org/10.1038/s41467-025-67957-1
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DOI: https://doi.org/10.1038/s41467-025-67957-1
