Unusual charge density wave and superconductivity in kagome metals AV₃Sb₅ (A = K, Rb, Cs)

The kagome metals AV₃Sb₅ (A = K, Rb, Cs) exhibit a host of intriguing phenomena, including a Z₂ nontrivial topological band structure, unconventional superconductivity, and charge density wave (CDW) states. These materials offer a unique platform to explore the interplay between lattice geometry, band topology, and electronic correlations. In this review, we focus on CDW, superconductivity, and the interactions between them in AV₃Sb₅. Additionally, we highlight several unresolved issues, such as the potential time-reversal symmetry breaking of 2×2 CDW, the nature of superconductivity (whether conventional or unconventional), and the underlying mechanism of CDW formation. We also summarize relevant experimental and theoretical evidence related to these topics. Our aim is to provide researchers with essential insights into CDW, superconductivity, and the outstanding questions surrounding AV₃Sb₅ for future investigations.