Observation of chiral and slow plasmons in twisted bilayer graphene

Tianye Huang, Xuecou Tu, Changqing Shen, Binjie Zheng, Junzhuan Wang, Hao Wang, Kaveh Khaliji, Sang Hyun Park, Zhiyong Liu, Teng Yang, Zhidong Zhang, Lei Shao, Xuesong Li, Tony Low, Yi Shi, Xiaomu Wang

Research output: Contribution to journalArticlepeer-review

31 Scopus citations

Abstract

Moiré superlattices have led to observations of exotic emergent electronic properties such as superconductivity and strong correlated states in small-rotation-angle twisted bilayer graphene (tBLG)1,2. Recently, these findings have inspired the search for new properties in moiré plasmons. Although plasmon propagation in the tBLG basal plane has been studied by near-field nano-imaging techniques3–7, the general electromagnetic character and properties of these plasmons remain elusive. Here we report the direct observation of two new plasmon modes in macroscopic tBLG with a highly ordered moiré superlattice. Using spiral structured nanoribbons of tBLG, we identify signatures of chiral plasmons that arise owing to the uncompensated Berry flux of the electron gas under optical pumping. The salient features of these chiral plasmons are shown through their dependence on optical pumping intensity and electron fillings, in conjunction with distinct resonance splitting and Faraday rotation coinciding with the spectral window of maximal Berry flux. Moreover, we also identify a slow plasmonic mode around 0.4 electronvolts, which stems from the interband transitions between the nested subbands in lattice-relaxed AB-stacked domains. This mode may open up opportunities for strong light–matter interactions within the highly sought after mid-wave infrared spectral window8. Our results unveil the new electromagnetic dynamics of small-angle tBLG and exemplify it as a unique quantum optical platform.

Original languageEnglish (US)
Pages (from-to)63-68
Number of pages6
JournalNature
Volume605
Issue number7908
DOIs
StatePublished - May 5 2022

Bibliographical note

Funding Information:
This project was primarily supported by the National Key R&D Program of China (2018YFA0307300, 2018YFA0209100 and 2017YFA0206301), the National Natural Science Foundation of China (61934004 and 62005119), the Program for High-Level Entrepreneurial and Innovative Talent Introduction of Jiangsu Province, the Strategic Priority Research Program of the Chinese Academy of Sciences (grant no. XDB30000000) and the Fundamental Research Funds for the Central Universities. X.L acknowledges the Shenzhen Science and Technology Program (No. (2021)105). L.S. acknowledges financial support from the National Natural Science Foundation of China (NSAF, U1930402) and computational resources from the Beijing Computational Science Research Center. We also thank the NJU micro-fabrication and integration centre for support.

Funding Information:
This project was primarily supported by the National Key R&D Program of China (2018YFA0307300, 2018YFA0209100 and 2017YFA0206301), the National Natural Science Foundation of China (61934004 and 62005119), the Program for High-Level Entrepreneurial and Innovative Talent Introduction of Jiangsu Province, the Strategic Priority Research Program of the Chinese Academy of Sciences (grant no. XDB30000000) and the Fundamental Research Funds for the Central Universities. X.L acknowledges the Shenzhen Science and Technology Program (No. (2021)105). L.S. acknowledges financial support from the National Natural Science Foundation of China (NSAF, U1930402) and computational resources from the Beijing Computational Science Research Center. We also thank the NJU micro-fabrication and integration centre for support.

Publisher Copyright:
© 2022, The Author(s), under exclusive licence to Springer Nature Limited.

PubMed: MeSH publication types

  • Journal Article
  • Research Support, Non-U.S. Gov't

Fingerprint

Dive into the research topics of 'Observation of chiral and slow plasmons in twisted bilayer graphene'. Together they form a unique fingerprint.

Cite this