Angle-resolved photoemission spectroscopy study on kagome superconductor AV3Sb5 (A = K, Rb, Cs)

The recently discovered kagome superconductors AV(3)Sb(5) (A= K, Rb, Cs) provide a new platform to explore intertwined symmetry-breaking orders. However, great controversies exist to date, including the origin of charge density wave (CDW), the unconventional or conventional nature of superconductivity, and the presence or absence of time-reversal symmetry breaking. A thorough understanding of the fundamental electronic structure is crucial for addressing these disputes. In this review, we provide an extensive summary of the key structural and electronic properties of AV(3)Sb(5) compounds and evaluate the current research on their unconventional electronic order, especially the superconductivity and CDW, with a particular focus on insights from angle-resolved photoemission spectroscopy studies. We expect this review to be timely due to the convergence of various experimentally observed phenomena related to the CDW and superconducting order parameters in AV(3)Sb(5) compounds. Our goal is to guide future investigations aimed at uncovering the microscopic origins of these unconventional electronic properties in kagome superconductors.