Correlated Dirac Fermions on the Honeycomb Lattice studied within Cluster Dynamical Mean Field Theory

Abstract

The role of non-local Coulomb correlations in the honeycomb lattice is investigated within cluster dynamical mean field theory combined with finite-temperature exact diagonalization. The paramagnetic semi-metal to insulator transition is found to be in excellent agreement with finite-size determinantal Quantum Monte Carlo simulations and with cluster dynamical mean field calculations based on the continuous-time Quantum Monte Carlo approach. As expected, the critical Coulomb energy is much lower than within a local or single-site formulation. Short-range correlations are shown to give rise to a pseudogap and concomitant non-Fermi-liquid behavior within a narrow range below the Mott transition.