Reconstructed twisted bilayer graphene (rTBG), predominant in low twist angles, is a novel system, where local phenomena related to electronic/phononic reconstructions in addition to the morphology rearrangement are yet to be understood. Here, we use a nano-Raman technique to explore aspects of phonon and electron-phonon localization in rTBG samples. Moreover, the inelastic scattering of light in the nano-Raman spectroscope allows the observation of the rTBG crystallographic structure with visible light. This result is possible due to lattice dynamics localization, the images resembling spectral variations caused by the presence of strain solitons and topological points. We support our findings with nearly-free phonon and electronic structure models that are at the state-of-the-art of calculation technologies to address this complex twistronics problem. Our discovery plays a role in many important phonon-related effects, and it may be useful for characterizing devices in the most prominent platform for the fast-developing field of twistronics.

Reference: https://arxiv.org/abs/2006.09482.

Andreij C. Gadelha

Universidade Federal de Minas Gerais (UFMG)