title: Is graphene in vacuum an insulator?
abstract: We present evidence, from lattice Monte Carlo simulations of the phase diagram of graphene as a function of the Coulomb coupling between quasiparticles, that graphene in vacuum is likely to be an insulator. We find a semimetal-insulator transition at alpha_{g};{crit}=1.11+/-0.06, where alpha_{g} approximately 2.16 in vacuum, and alpha_{g} approximately 0.79 on a SiO2 substrate. Our analysis uses the logarithmic derivative of the order parameter, supplemented by an equation of state. The insulating phase disappears above a critical number of four-component fermion flavors 4<N_{f};{crit}<6. Our data are consistent with a second-order transition.
authors.affiliation: Department of Physics, The Ohio State University, Columbus, Ohio 43210-1117, USA.
authors.forename: Joaquín E
authors.initials: JE
authors.lastname: Drut
authors.forename: Timo A
authors.initials: TA
authors.lastname: Lähde