Chiral charge order in kagome superconductor AV3Sb5

Kagome lattice has been introduced to quantum physics for seventy years. Over recent years, kagome lattice has been demonstrated as a novel quantum platform displaying unprecedented intertwining between lattice geometry, competing orders, and electronic topology [Nature555, 638-642 (2018); Nature562, 91-95(2018); Nature Physics, 443 (2019); Nature583, 533-536 (2020); Nature Review Physics, 249-263 (2021)]. While most of these materials exhibit quantum magnetism, the observation of chiral charge order in kagome superconductor AV3Sb5 (A=K, Cs, Sb) further pushes the research of kagome lattice to the quantum frontier. In this talk, I will present our scanning tunneling microscopy evidence of chiral charge order in all three AV3Sb5 compounds. This discovery is further supported by our muon spin rotation experiment which is bulk and extremely magnetic sensitive. I will discuss relevance of the chiral charge order to the Haldane model for the quantum anomalous Hall effect and Varma model for the hidden phase in cuprate high temperature superconductors.