Raman spectra of twisted bilayer graphene close to the magic angle

Abstract

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${}^{\circ }$ to 3.40${}^{\circ }$, 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${}^{\circ }$ regime is dictated by crystal lattice and depends on both the Bernal (AB and BA) stacking bilayer graphene and strain soliton regions (SP). 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.

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Cited by in corpus (8)

• Symmetry Origin of Lattice Vibration Modes in Twisted Multilayer Graphene: Phasons vs Moiré Phonons
• An atomistic insight into moiré reconstruction in Twisted Bilayer Graphene beyond the magic angle
• Probing interlayer interactions and commensurate-incommensurate transition in twisted bilayer graphene through Raman spectroscopy
• Electron-phonon coupling in a magic-angle twisted-bilayer graphene device
• Anomalies in G and 2D Raman Modes of Twisted Bilayer Graphene Near the Magic Angle
• Interference effects in polarization controlled Rayleigh scattering in twisted bilayer graphene
• Direct observation of flat bands in near-magic-angle twisted bilayer CVD graphene
• Electronic properties of twisted multilayer graphene