Interacting Dirac fermions on honeycomb lattice

We investigate the interacting Dirac fermions on honeycomb lattice by cluster dynamical mean-field theory (DMFT) combined with continuous-time quantum Monte Carlo simulation. A novel scenario for the semimetal-Mott insulator transition of the interacting Dirac fermions is found beyond the previous DMFT studies. Our results suggest that for weak interaction, the system is semimetal and the Fermi velocity keeps constant. The system undergoes a second-order Mott transition with increasing the interaction strength. We demonstrate that the nonlocal spatial correlations play a vital role in the Mott transition on the honeycomb lattice. A phase diagram of Mott transition is presented. We also elaborate the experimental protocol to observe this phase transition by the ultracold atoms on optical honeycomb lattice.