Phonon spectroscopy through the electronic density of states in graphene

In contrast to the normal state of conventional metals for which phonon renormalizations drop out of the electronic density of states, we demonstrate that they remain in the case of graphene and their signature is large and measurable. Furthermore, the electron-phonon interaction, which is fixed in conventional metals, can be tuned over a significant range in graphene by changing the gate voltage. Indeed, a factor of 2 in magnitude should be easily achievable. These two features allow for a normal-state spectroscopy for examining many-body interactions, such as the electron-phonon interaction. We present a procedure to trace the magnitude of the amplitude of the predicted phonon structures which will increase significantly with increasing doping. We also find that the Dirac point zero in the electronic density of states can be lifted and will become quadratic signifying the presence of many-body renormalizations in graphene.