Fermi surface topology and interlayer modulation of charge density waves in the kagome material CsV₃Sb₅

The recently discovered kagome materials AV₃Sb₅ (A = K, Rb, Cs) attract intense research interest in intertwined topology, superconductivity, and charge density waves (CDW). Although the in-plane 2x2 CDW is well studied, the electronic properties induced by the structural modulation between neighboring kagome layers are less understood. In this work, we investigated the Fermi surface reconstruction and topology in the presence of interlayer CDW (2x2x2) on CsV₃Sb₅ by theoretical calculations. We derived Fermi-energy-resolved and layer-resolved quantum orbits that agree quantitatively with experimental results. We found that Dirac nodal lines and Dirac networks, a topological feature beyond the Z₂ topology, induce a π Berry phase for several quantum orbits. Our work reveals the quasi-two-dimensional nature of Fermi surfaces and the rich topological nature of kagome materials.