Topological Flat Bands in 2D Breathing-Kagome Lattice Nb3 TeCl7

Hongrun Zhang; Zhijian Shi; Zhicheng Jiang; Ming Yang; Jingwei Zhang; Ziyuan Meng; Tonghua Hu; Fucai Liu; Long Cheng; Yong Xie; Jincheng Zhuang; Haifeng Feng; Weichang Hao; Dawei Shen; Yi Du

doi:10.1002/adma.202301790

Topological Flat Bands in 2D Breathing-Kagome Lattice Nb₃ TeCl₇

Adv Mater. 2023 Oct;35(41):e2301790. doi: 10.1002/adma.202301790. Epub 2023 Sep 3.

Authors

Hongrun Zhang^{1

2}, Zhijian Shi^{1

2}, Zhicheng Jiang³, Ming Yang^{1

2}, Jingwei Zhang^{1

2}, Ziyuan Meng^{1

2}, Tonghua Hu¹, Fucai Liu⁴, Long Cheng^{1

2

5}, Yong Xie^{1

6}, Jincheng Zhuang^{1

2}, Haifeng Feng^{1

2}, Weichang Hao^{1

2}, Dawei Shen^{3

7}, Yi Du^{1

2}

Affiliations

¹ School of Physics, Beihang University, Beijing, 100191, P. R. China.
² Centre of Quantum and Matter Sciences, International Research Institute for Multidisciplinary Science, Beihang University, Beijing, 100191, P. R. China.
³ State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, P. R. China.
⁴ School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, 611731, P. R. China.
⁵ Beijing Key Laboratory of Advanced Nuclear Materials and Physics, Beihang University, Beijing, 100191, P. R. China.
⁶ Key Laboratory of Intelligent Systems and Equipment Electromagnetic Environment Effect, School of Electronic and Information Engineering, Beihang University, Beijing, 100191, P. R. China.
⁷ National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, 230029, P. R. China.

PMID: 37497878
DOI: 10.1002/adma.202301790

Abstract

Flat bands (FBs) can appear in two-dimensional (2D) geometrically frustrated systems caused by quantum destructive interference (QDI). However, the scarcity of pure 2D frustrated crystal structures in natural materials makes FBs hard to be identified, let alone modulate FBs relating to electronic properties. Here, the experimental evidence of the complete electronic QDI induced FB contributed by the 2D breathing-kagome layers of Nb atoms in Nb₃ TeCl₇ (NTC) is reported. An identical chemical state and 2D localization characteristics of the Nb breathing-kagome layers are experimentally confirmed, based on which NTC is demonstrated to be a superior concrete candidate for the breathing-kagome tight-binding model. Furthermore, it theoretically establishes the tunable roles of the on-site energy over Nb sites on bandwidth, energy position, and topology of FBs in NTC. This work opens an aveanue to manipulate FB characteristics in these 4d transition-metal-based breathing-kagome materials.

Keywords: Nb3TeCl7; angle-resolved photoemission spectroscopy; breathing kagome; flat band; topological.

Abstract

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