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arXiv · 2309.03288

Intertwined van-Hove Singularities as a Mechanism for Loop Current Order in Kagome Metals

Heqiu Li·Yong Baek Kim·Hae-Young Kee
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Abstract

Recent experiments on Kagome metals AV$_3$Sb$_5$ (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 AV$_3$Sb$_5$. Our findings provide an intriguing mechanism of LCO and pave the way for a deeper understanding of complex quantum phenomena in Kagome systems.

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Heqiu Li, Yong Baek Kim, Hae-Young Kee. 2023-09-06. Intertwined van-Hove Singularities as a Mechanism for Loop Current Order in Kagome Metals. https://doi.org/10.1103/physrevlett.132.146501

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