▎ 摘　　要

Doping epitaxial graphene on SiC(0001) using nitrogen plasma leads to N-vacancy complexes. Based on the calculated energetics by density functional theory and comparison with scanning tunneling microscopy observations, the most probable configuration is determined to be a nonmagnetic complex consisting of substitutional nitrogen next to a carbon vacancy. Further calculations show that other N-vacancy complexes, where the substituted N and the vacancy are the second and third nearest neighbors, do exhibit localized moments. These results indicate that the electronic and magnetic properties of graphene can be further tailored by plasma-assisted nitrogen doping. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4726281]