Local spectroscopy of loop current order in a kagome metal

The zip file contains the raw data for Figs. 1-4 and Ext. Data Figs. 1 and 2 of the main text. All data processing to obtain the final plots are described in the main text, Methods section, and Suppl. Materials. All other data that support the findings of this study are available from the corresponding authors upon request Abstract Hidden ordered states are characterized by order parameters that conventional probes do not couple to and are therefore difficult to identify in quantum materials. Recent experiments report evidence for one such hidden order: a time-reversal symmetry breaking orbital magnetic order in the charge density wave state of the kagome metal CsV3Sb5. Theoretical analyses propose that a loop-current order could exist as the ground state of this charge density wave, but this microscopic interpretation is still under debate. Here, we provide spectroscopic evidence of a loop current ordered state in this compound. Using individual magnetic atoms as local quantum sensors in a scanning tunneling microscope, we probe the quasiparticle excitations of the charge density wave in CsV3Sb5. We find that the magnetic moment of Co induces a spatially localized differential conductance peak within the charge-density-wave gap near the Fermi energy. Comparison of our experimental observations with theoretical calculations suggests a local flux defect in a loop current ordered state that arises from the Kondo coupling of the magnetic moment of Co with the loop current electrons. Our results provide a microscopic picture to the observation of time-reversal symmetry breaking orbital magnetism and anomalous transport signatures observed in this kagome material.