Discovery of AV3Sb5 kagome superconductors and CsV3Sb5 Fermi surface mapping*

Since our discovery of the AV₃Sb₅ (A: K, Rb Cs) family of kagome superconductors, the system has garnered significant attention within the condensed matter physics community, particularly due to the unique combination of nontrivial band topology, superconductivity, and signatures of electron correlations manifest via competing charge density wave order.  Still, little is understood regarding the nature of the charge density wave (CDW) instability inherent to these compounds. To understand the impact of the CDW order on the electronic structure in these systems, we present quantum oscillation measurements on single crystals of CsV₃Sb₅. Our data provide direct evidence that the CDW invokes a substantial reconstruction of the Fermi surface pockets associated with the vanadium orbitals and the kagome lattice framework.  Complementary diffraction measurements are further able to demonstrate that the CDW instability has a correlated phasing of distortions, and the average structure in the CDW state is proposed.