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Free keywords:
Crystal symmetry; Electronic structure; Iron compounds; Iron-based Superconductors; Photoelectron spectroscopy; Selenium compounds; Surface states; Tellurium compounds; Topology; Angle resolved photoemission spectroscopy; Band inversion; Bulk electronic structures; Condensed-matter physics; Orbitals; Renormalization; Spectral weight; Tight-binding modeling; Topological bands; Unconventional superconductivity; Band structure
Abstract:
FeTe0.55Se0.45 (FTS) occupies a special spot in modern condensed matter physics at the intersections of electron correlation, topology, and unconventional superconductivity. The bulk electronic structure of FTS is predicted to be topologically nontrivial due to the band inversion between the dxz and pz bands along Γ-Z. However, there remain debates in both the authenticity of the Dirac surface states (DSSs) and the experimental deviations of band structure from the theoretical band inversion picture. Here we resolve these debates through a comprehensive angle-resolved photoemission spectroscopy investigation. We first observe a persistent DSS independent of kz. Then, by comparing FTS with FeSe, which has no band inversion along Γ-Z, we identify the spectral weight fingerprint of both the presence of the pz band and the inversion between the dxz and pz bands. Furthermore, we propose a renormalization scheme for the band structure under the framework of a tight-binding model preserving crystal symmetry. Our results highlight the significant influence of correlation on modifying the band structure and make a strong case for the existence of topological band structure in this unconventional superconductor. © 2024 authors. Published by the American Physical Society.
