Electron-electron interactions and charging effects in graphene quantum dots

We analyze charging effects in graphene quantum dots. Using a simple model, we show that when the Fermi level is far from the neutrality point, charging effects lead to a shift in the electrostatic potential and the dot shows standard Coulomb blockade features. Near the neutrality point, surface states are partially occupied and the Coulomb interaction leads to a strongly correlated ground state, which can be approximated by either a Wigner crystal or a Laughlin-like wave function. The existence of strong correlations modifies the transport properties, which show nonequilibrium effects, similar to those predicted for tunneling into other strongly correlated systems.