Kagome superconductors AV3Sb5 (A = K, Rb, Cs)

The quasi-two-dimensional kagome materials AV(3)Sb(5) (A = K, Rb, Cs) were found to be a prime example of kagome superconductors, a new quantum platform to investigate the interplay between electron correlation effects, topology and geometric frustration. In this review, we report recent progress on the experimental and theoretical studies of AV(3)Sb(5) and provide a broad picture of this fast-developing field in order to stimulate an expanded search for unconventional kagome superconductors. We review the electronic properties of AV(3)Sb(5), the experimental measurements of the charge density wave state, evidence of time-reversal symmetry breaking and other potential hidden symmetry breaking in these materials. A variety of theoretical proposals and models that address the nature of the time-reversal symmetry breaking are discussed. Finally, we review the superconducting properties of AV(3)Sb(5), especially the potential pairing symmetries and the interplay between superconductivity and the charge density wave state. In this review, the authors report recent progress on the experimental and theoretical studies of kagome superconductor AV(3)Sb(5), which opens a new route towards unconventional orders in kagome metals.