Time: 14:00, May 7 (Tuesday) 2024

Location：Rm N108, UCAS Teaching Building. Tencent Meeting ID: 247-018-388

                   教学楼N108（中关村校区）or（腾讯会议：247-018-388）

Speaker：Heqiu Li (李河虬) （University of Toronto）

Abstract:

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.

References:

[1] Heqiu Li, Yong Baek Kim, Hae-Young Kee, “Intertwined van-Hove singularities as a mechanism for loop current order in kagome metals”, Phys. Rev. Lett. 132, 146501 (2024)

[2] Heqiu Li, Xiaoyu Liu, Yong Baek Kim, Hae-Young Kee, “Origin of π-shifted three-dimensional charge density waves in kagome metal AV3Sb5”, Phys. Rev. B 108, 075102 (2023)