Electron-phonon interactions for optical-phonon modes in few-layer graphene: First-principles calculations

We present a first-principles study of the electron-phonon (e-ph) interactions and their contributions to the linewidths for the optical-phonon modes at Γ and K in one-layer to three-layer graphene. It is found that, due to the interlayer coupling and the stacking geometry, the high-frequency optical-phonon modes in few-layer graphene couple with different valence and conduction bands, giving rise to different e-ph interaction strengths for these modes. Some of the multilayer optical modes derived from the Γ-E2g mode of monolayer graphene exhibit slightly higher frequencies and much reduced linewidths. In addition, the linewidths of K-A₁^' related modes in multilayers depend on the stacking pattern and decrease with increasing layer numbers.