Temperature-Driven Rotation Symmetry-Breaking States in an Atomic Kagome Metal KV 3 Sb 5 .

Kagome lattice AV 3 Sb 5 has attracted tremendous interest because it hosts correlated and topological physics. However, an in-depth understanding of the temperature-driven electronic states in AV 3 Sb 5 is elusive. Here we use scanning tunneling microscopy to directly capture the rotational symmetry-breaking effect in KV 3 Sb 5 . Through both topography and spectroscopic imaging of defect-free KV 3 Sb 5 , we observe a charge density wave (CDW) phase transition from an a 0 × a 0 atomic lattice to a robust 2 a 0 × 2 a 0 superlattice upon cooling the sample to 60 K. An individual Sb-atom vacancy in KV 3 Sb 5 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 KV 3 Sb 5 , highlighting the multiorbital correlation in the kagome lattice framework.