Twofold van Hove singularity and origin of charge order in topological kagome superconductor CsV3Sb5

The layered vanadium antimonides AV3Sb5 (A = K, Rb, Cs) are a recently discovered family of topological kagome metals that exhibit range strongly correlated electronic phases including charge order and superconductivity. However, it is not yet understood how the distinctive structure lattice linked to observed many-body phenomena. Here we combine angle-resolved photoemission spectroscopy density functional theory reveal multiple kagome-derived van Hove singularities (vHS) coexisting near Fermi level CsV3Sb5 analyse their contribution symmetry breaking. vHS characterized by two distinct sublattice flavours (p-type m-type), which originate, respectively, from pure mixed characters. These twofold critically determine pairing unconventional ground states emerging in series. We establish that, among CsV3Sb5, m-type dxz/dyz band p-type dxy/dx2–y2 located very close level, setting stage for former pronounced surface nesting, while latter exhibits higher-order vHS. Our work reveals essential role collective phenomena realized family. Spectroscopic measurements show features related contribute phases.