ABSTRACT
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. We propose a microscopic mechanism to explain the emergence of LCO through electronic correlations. We show that the coupling between van-Hove singularities (vHS) with distinct 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.
BIOGRAPHY
Dr. Heqiu Li is a condensed matter theorist specializing in topological phases and strongly correlated electronic systems. He received his B.Sc. from Zhejiang University and his Ph.D. from the University of Michigan, where he developed foundational formalisms for higher-order topological insulators under the guidance of Prof. Kai Sun. Following postdoctoral positions at the University of Toronto and now at the Donostia International Physics Center, Dr. Li’s research has unveiled mechanisms for emergent phases in moiré superlattices, kagome metals, and rhombohedral multilayer graphene, often in collaboration with leading theorists such as B. Andrei Bernevig and Y.B. Kim. His pioneering work on fractional Chern insulators and loop current orders bridges exact diagonalization techniques and innovative symmetry analysis, garnering recognition across premier journals like Physical Review Letters.
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