The importance of phonons in the strong correlation phenomena observed in twisted-bilayer
graphene (TBG) at the so-called magic-angle is under debate. Here a gate-dependent micro-Raman spectroscopy to
monitor the G band line width was applied in TBG devices of twist angles θ = 0° (Bernal), ∼1.1° (magic-angle), and ∼7°
(large-angle). The results show a broad and p-/n-asymmetric doping behavior at the magic angle, in clear contrast to the
behavior observed in twist angles above and below this point. Atomistic modeling perfumed by Dr. Viet-Hung Nguyen
(from the group of JC Charlier in MODL) reproduces the experimental observations in close connection with the joint
density of electronic states in the electron−phonon scattering process, revealing how the unique electronic structure of
magic-angle TBGs influences the electron−phonon coupling and, consequently, the G band line width.
Reference : Andreij C. Gadelha, Viet-Hung Nguyen, Eliel G. S. Neto, Fabiano Santana, Markus B. Raschke, Michael
Lamparski, Vincent Meunier, Jean-Christophe Charlier, and Ado Jorio, Nano Letters 22, 6069-6074 (2022)