Band structures for (a) one and (b) two graphene layers on SiC(0001) with the first graphene layer doped by six F atoms. The blue and red curves represent the majority and minority spin, respectively. (c) Spin density (ρ=ρ↑ −ρ↓) isosurfaces of the six F atoms decorated single layer epitaxial graphene. The isosurface is 0.025 e/ų.