中国物理B ›› 2023, Vol. 32 ›› Issue (10): 107302-107302.doi: 10.1088/1674-1056/acb2c1

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Effects of strain on the flat band in twisted bilayer graphene

Zhen Zhang(张镇), Lu Wen(文露), Youkai Qiao(乔友凯), and Zhiqiang Li(李志强)   

  1. College of Physics, Sichuan University, Chengdu 610064, China
  • 收稿日期:2022-09-16 修回日期:2023-01-10 接受日期:2023-01-13 出版日期:2023-09-21 发布日期:2023-09-27
  • 通讯作者: Zhiqiang Li E-mail:zhiqiangli@scu.edu.cn
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant No. 11874271). We thank Yan He for theoretical support and discussions.

Effects of strain on the flat band in twisted bilayer graphene

Zhen Zhang(张镇), Lu Wen(文露), Youkai Qiao(乔友凯), and Zhiqiang Li(李志强)   

  1. College of Physics, Sichuan University, Chengdu 610064, China
  • Received:2022-09-16 Revised:2023-01-10 Accepted:2023-01-13 Online:2023-09-21 Published:2023-09-27
  • Contact: Zhiqiang Li E-mail:zhiqiangli@scu.edu.cn
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No. 11874271). We thank Yan He for theoretical support and discussions.

摘要: Based on the effective continuum model, we systematically study the electronic band structures and density of states of twisted bilayer graphene near the magic angle under the influence of different types of strain, including shear strain, volume-preserving strain and biaxial strain. We find that the flat bands behave very differently under various types of strain. Volume-preserving strain generically leads to broader van Hove singularities associated with the flat bands compared with those under shear strain, with dissimilar strain direction dependence. The band structures and density of states under shear and volume-preserving strains change with the strain direction, while those under biaxial strain are independent of the direction of strain. In particular, the effect of biaxial strain on twisted bilayer graphene is geometrically and electronically similar to the influence of the twisted angle. Our results reveal the characteristic structures in the band structures and density of states under various types of strain, which can serve as fingerprints for exploring the effects of strain on the novel physics of this system.

关键词: graphene, moiré superlattice, magic angle and strain

Abstract: Based on the effective continuum model, we systematically study the electronic band structures and density of states of twisted bilayer graphene near the magic angle under the influence of different types of strain, including shear strain, volume-preserving strain and biaxial strain. We find that the flat bands behave very differently under various types of strain. Volume-preserving strain generically leads to broader van Hove singularities associated with the flat bands compared with those under shear strain, with dissimilar strain direction dependence. The band structures and density of states under shear and volume-preserving strains change with the strain direction, while those under biaxial strain are independent of the direction of strain. In particular, the effect of biaxial strain on twisted bilayer graphene is geometrically and electronically similar to the influence of the twisted angle. Our results reveal the characteristic structures in the band structures and density of states under various types of strain, which can serve as fingerprints for exploring the effects of strain on the novel physics of this system.

Key words: graphene, moiré superlattice, magic angle and strain

中图分类号:  (Electronic structure of graphene)

  • 73.22.Pr
73.21.Cd (Superlattices) 81.05.ue (Graphene)