Electron-phonon coupling in potassium-doped graphene: Angle-resolved photoemission spectroscopy

The electron-phonon coupling in potassium-doped graphene on Ir(111) is studied via the renormalization of the ${\ensuremath{\pi}}^{\ensuremath{\ast}}$ band near the Fermi level, using angle-resolved photoemission spectroscopy. The renormalization is found to be fairly weak and almost isotropic, with a mass enhancement parameter of $\ensuremath{\lambda}=0.28(6)$ for both the $\overline{K}\ensuremath{-}\overline{M}$ and the $\overline{K}\ensuremath{-}\overline{\ensuremath{\Gamma}}$ direction. These results are found to agree well with recent first-principles calculations.