Magnetism and Interaction-Induced Gap Opening in Graphene with Vacancies or Hydrogen Adatoms: Quantum Monte Carlo Study

We study the electronic properties of graphene with a finite concentration of vacancies or other resonant scatterers by a straightforward lattice quantum Monte Carlo calculation. Taking into account a realistic long-range Coulomb interaction, we calculate the distribution of the spin density associated with midgap states and demonstrate antiferromagnetic ordering. An energy gap is open due to interaction effects, both in the bare graphene spectrum and in the vacancy or impurity bands. In the case of a 5% concentration of resonant scatterers the latter gap is estimated to be 0.7 eV and 1.1 eV for graphene on boron nitride and freely suspended graphene, respectively.