• 文献标题:   Raman spectra of twisted bilayer graphene close to the magic angle
  • 文献类型:   Article
  • 作  者:   BARBOSA TC, GADELHA AC, OHLBERG DAA, WATANABE K, TANIGUCHI T, MEDEIROSRIBEIRO G, JORIO A, CAMPOS LC
  • 作者关键词:   raman spectroscopy, twisted bilayer graphene, magic angle
  • 出版物名称:   2D MATERIALS
  • ISSN:   2053-1583
  • 通讯作者地址:  
  • 被引频次:   4
  • DOI:   10.1088/2053-1583/ac4af9
  • 出版年:   2022

▎ 摘  要

In this work, we study the Raman spectra of twisted bilayer graphene samples as a function of their twist-angles (theta), ranging from 0.03 degrees to 3.40 degrees, where local theta are determined by analysis of their associated moire superlattices, as imaged by scanning microwave impedance microscopy. Three standard excitation laser lines are used (457, 532, and 633 nm wavelengths), and the main Raman active graphene bands (G and 2D) are considered. Our results reveal that electron-phonon interaction influences the G band's linewidth close to the magic angle regardless of laser excitation wavelength. Also, the 2D band lineshape in the theta < 1 degrees regime is dictated by crystal lattice and depends on both the Bernal (AB and BA) stacking bilayer graphene and strain soliton regions (SP) (Gadelha et al 2021 Nature 590 405-9). We propose a geometrical model to explain the 2D lineshape variations, and from it, we estimate the SP width when moving towards the magic angle.