Common Sublattice-Pure Van Hove Singularities in the Kagome Superconductors A V 3 Sb 5 ( A = K , Rb, Cs)

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Abstract
Kagome materials offer a versatile platform for exploring correlated and topological quantum states, where Van Hove singularities (VHSs) play a pivotal role in driving electronic instabilities, exhibiting distinct behaviors depending on electron filling and interaction settings. In the recently discovered kagome superconductors AV_{3}Sb_{5} (A=K, Rb, Cs), unconventional charge density wave order, superconductivity, and electronic chirality emerge, yet the nature of VHSs near the Fermi level (E_{F}) and their connection to these exotic orders remain elusive. Here, using high-resolution polarization-dependent angle-resolved photoemission spectroscopy, we uncover a universal electronic structure across AV_{3}Sb_{5} that is distinct from density-functional theory predictions that show noticeable discrepancies. We identify multiple common sublattice-pure VHSs near E_{F}, arising from strong V-d/Sb-p hybridization, which significantly promote bond-order fluctuations and likely drive the observed charge density wave order. These findings provide direct spectroscopic evidence for hybridization-driven VHS formation in kagome metals and establish a unified framework for understanding the intertwined electronic instabilities in AV_{3}Sb_{5}.
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Funding Information
  • National Natural Science Foundation of China (12574156)
  • National Natural Science Foundation of China (12574151)
  • National Natural Science Foundation of China (12447103)
  • National Natural Science Foundation of China (12447101)
  • National Natural Science Foundation of China (12350710785)
  • Fundamental Research Funds for the Central Universities (00130452020006)
  • Fundamental Research Funds for the Central Universities (226-2024-00068)
  • Chongqing University (0013045203003)
  • University of California, Santa Barbara (DMR-1906325)
  • U.S. Department of Energy
  • Office of Science
  • Basic Energy Sciences
  • Materials Sciences and Engineering Division
  • RIKEN
  • National Key Research and Development Program of China (2023YFA1407300)
  • Xiaomi Young Talents Program

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