2025/03/24 by Zheng, Jiangchang, Chen, Caiyun, Pan, Gaopei +11
#FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #Strongly Correlated Electrons (cond-mat.str-el)
paper · doi:10.48550/arxiv.2503.19032
Electronic interactions can give rise to novel charge density waves with unconventional ground states. Recent experiments report evidence for a chiral charge density wave (CDW) that breaks time-reversal symmetry in the kagome metals AV3Sb5 (A=K, Rb or Cs). Theoretical analyses propose a topologically nontrivial loop current phase that spontaneously breaks time-reversal symmetry as the favorable CDW ground state. However, spectroscopic insights into the quasiparticle excitations of chiral charge order in AV3Sb5 compounds are still missing and conflicting experimental results question the presence of a loop current phase. We employed individual magnetic atoms as local quantum sensors to examine the quasiparticle excitations of chiral charge order in CsV3Sb5 with the scanning tunneling microscope (STM). Our spectroscopic measurements show that the magnetic moment of Co induces a spatially-localized low-energy state in the CDW phase. The distinct spectral signatures of this state are consistent with theoretical expectations for the quasiparticle excitation of a loop current order parameter, while control experiment rule out alternative scenario. Our work provides unique insights into the ground state of chiral charge order in CsV3Sb5 and introduces a novel method to examine other topological states, such as the fractional Chern insulators, with the STM.