Edge Raman Modes in Crumpled Few-Layer Twisted Graphene

Dmytro Nikolaievskyi 1, Olivier Chuzel1, Cédric Pardanaud2

1Aix Marseille Univ, CNRS, Centrale Marseille, iSm2, Marseille, France, 2Aix Marseille Univ, CNRS, PIIM, Marseille, France.

Graphene samples occurring in laboratory and industrial practice often contain defects, strain, wrinkles, crumples and are not single layer. The influence of twist angle between graphene layers, wrinkles, and corrugations on graphene's electronic properties lies in the base of emerging fields of twistronics and straintronics. Herein, we create and study highly crumpled twisted few- and multilayer CVD graphene samples by Raman and electronic microscopies.1,2) Their Raman spectra (633 nm laser), besides traditionally present D, G and 2D bands, contain 23 low intensity bands between 600 and 3100 cm-1. 12 of these bands are situated between 600 and 1200 cm-1, and other 11 bands laying at higher wavenumbers can be explained as second harmonics or combinations. We analyze different explanations of their origin showing that the edge phonons mechanism is the most plausible. Complete elucidation of physical mechanism behind these bands will allow to use them as supplementary of criterium of graphene quality.

References:

1) C. Pardanaud et al. J. Phys. Chem. Lett. 2019, 10, 3571.

2) D. Nikolaievskyi et al., Carbon 2023, 203, 650.