Intralayer and interlayer electron-phonon interactions in twisted bilayer graphene

In this work we report on the possibility of using resonance Raman spectroscopy to distinguish intralayer and interlayer electron-phonon (el-ph) interactions in twisted bilayer graphene (TBG). This is experimentally attained by tuning the energy of the excitation photon and observing the resonances of the Raman modes in different samples of TBGs. In the intralayer process, the el-ph scattering occurs in a single graphene layer and the other layer imposes a periodic potential that back scatters the excited electron, whereas for the interlayer process the el-ph scattering occurs between states in the Dirac cones of adjacent graphene layers. Our methodology can be extended to study any kind of graphene-based heterostructure. [Eliel et al., Nature Comm. 9, 1221 (2018)]