Observation of Carrier-Density-Dependent Many-Body Effects in Graphene via Tunneling Spectroscopy

We find the scanning tunneling spectra of backgated graphene monolayers to be significantly altered by many-body excitations. Experimental features in the spectra arising from electron-plasmon interactions show carrier density dependence, distinguishing them from density-independent electron-phonon features. Using a straightforward model, we are able to calculate theoretical tunneling spectra that agree well with our data, providing insight into the effects of many-body interactions on the lifetime of graphene quasiparticles.