The discovery of superconductivity in twisted bilayer graphene sparked interest in the electronic properties of similarly distorted 2D crystal lattices. The twisted structure is created by slightly rotating two crystal networks in bilayer graphene, but the resulting lattices need to be imaged at the atomic level for their properties to be understood. In collaboration with a Brazilian and an American teams, UCLouvain researchers (Dr. Viet-Hung Nguyen, Dawid Paszko, and Prof. Jean-Christophe Charlier) have investigated both experimentally and theoretically reconstructed twisted bilayer graphene below the magic angle in order to probe the vibrational modes of the lattice. Using visible light, the nano-Raman spectroscope revealed the localization of vibrational modes and allowed to study how these influence electronic properties as confirmed by numerical simulations. These results are a step towards understanding phonon-related effects and electronic localization in twisted bilayer graphene which could aid the development of ‘twistronics‘.
Nature website : https://www.nature.com/articles/s41586-021-03252-5