The tunneling density-of-states of interacting massless Dirac fermions

We calculate the tunneling density-of-states (DOS) of a disorder-free two-dimensional interacting electron system with a massless-Dirac band Hamiltonian. The DOS exhibits two main features: (i) linear growth at large energies with a slope that is suppressed by quasiparticle velocity enhancement, and (ii) a rich structure of plasmaron peaks which appear at negative bias voltages in an n-doped sample and at positive bias voltages in a p-doped sample. We predict that the DOS at the Dirac point is non-zero even in the absence of disorder because of electron–electron interactions, and that it is then accurately proportional to the Fermi energy. The finite background DOS observed at the Dirac point of graphene sheets and topological insulator surfaces can therefore be an interaction effect rather than a disorder effect.

► We calculate the tunneling DOS of two-dimensional disorder-free interacting massless Dirac fermions.
► It shows a linear growth with a slope suppressed by quasiparticle velocity enhancement.
► It shows a rich structure due to plasmaron satellite bands.
► e–e interactions induce a finite DOS at the Dirac point, even in the absence of disorder.
► e–e interaction contribution to the DOS is large compared to a typical disorder-induced background.