Recent experiments on Kagome metals AV3Sb5 (A=Cs,Rb,K) indicated spontaneous time-reversal symmetry breaking in the charge density wave state in the absence of static magnetization. The loop current order (LCO) is proposed as its cause, but a microscopic model explaining the emergence of LCO through electronic correlations has not been firmly established. We show that the coupling between van-Hove singularities (vHS) with distinct mirror symmetries is a key ingredient to generate LCO ground state. By constructing an effective model, we find that when multiple vHS with opposite mirror eigenvalues are close in energy, the nearest-neighbor electron repulsion favors a ground state with coexisting LCO and charge bond order. It is then demonstrated that this mechanism applies to the Kagome metals AV3Sb5. Our findings provide an intriguing mechanism of LCO and pave the way for a deeper understanding of complex quantum phenomena in Kagome systems.
@article{arxiv.2309.03288,
title = {Intertwined van-Hove Singularities as a Mechanism for Loop Current Order in Kagome Metals},
author = {Heqiu Li and Yong Baek Kim and Hae-Young Kee},
journal= {arXiv preprint arXiv:2309.03288},
year = {2024}
}