Temperature-Driven Rotation Symmetry-Breaking States in an Atomic Kagome Metal KV₃Sb₅

Kagome lattice AV₃Sb₅ has attracted tremendous interest because it hosts correlated and topological physics. However, an in-depth understanding of the temperature-driven electronic states in AV₃Sb₅ is elusive. Here we use scanning tunneling microscopy to directly capture the rotational symmetry-breaking effect in KV₃Sb₅. Through both topography and spectroscopic imaging of defect-free KV₃Sb₅, we observe a charge density wave (CDW) phase transition from an a₀ × a₀ atomic lattice to a robust 2a₀ × 2a₀ superlattice upon cooling the sample to 60 K. An individual Sb-atom vacancy in KV₃Sb₅ further gives rise to the local Friedel oscillation (FO), visible as periodic charge modulations in spectroscopic maps. The rotational symmetry of the FO tends to break at the temperature lower than 40 K. Moreover, the FO intensity shows an obvious competition against the intensity of the CDW. Our results reveal a tantalizing electronic nematicity in KV₃Sb₅, highlighting the multiorbital correlation in the kagome lattice framework.