香港大学-中国科学院大学 青年物理学者论坛

HKU-UCAS young physicist forum

 

本论坛由香港大学-中国科学院大学理论与计算物理联合研究所香港和北京分部共同承办。旨在促进青年物理学者互相的交流和讨论。不同于寻常的短平快形式的科学报告，我们主要集中于更为系统、全方位、由浅入深地讲解当前物理的各个前沿方向。报告人主要是目前活跃于科研一线的年轻学者。

 

This forum is hosted by the HKU-UCAS Joint Institute of Theoretical and Computational Physics at Hong Kong and Beijing. It aims to promote interchanges and discussions among young physicists. Different from ordinary scientific reports in the short, simple and quick form, we mainly focus on explaining and introducing various frontier directions of current physics in a more systematic, all-round way and from the shallower to the deeper. The speakers are mainly young scholars who are currently active in the front line of scientific research.

           

12^th forum（第十二期）

报告人简介

 

 

 

Heqiu Li (李河虬) is a postdoctoral fellow at University of Toronto. He received his PhD in physics at University of Michigan, Ann Arbor under the supervision of Prof. Kai Sun in 2021, and bachelor’s degree in physics at Zhejiang University in 2016. His current research interest includes: (1) Exotic phases such as charge density wave and superconductivity in kagome metals. (2) Strongly correlated phases in Moire superlattices. (3) Classification and diagnosis of topological phases of matter.

 

 

 

 

 

Abstract, time and venue:

 

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

 

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.

 

Date: 2023.11.01

Time: 10:00 AM (UTC+8)

Zoom link: https://hku.zoom.us/j/92670581106?pwd=WENmeUtZQzhyY3FrRUpUTXZLWDJHQT09

Zoom ID:  926 7058 1106 (password: 688232)

 

 

 

References:

[1] Heqiu Li, Yong Baek Kim, Hae-Young Kee, “Intertwined van-Hove singularities as a mechanism for loop current order in kagome metals”, arXiv: 2309.03288

[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)