Single-layer metallicity and interface magnetism of epitaxial graphene on SiC(0001)

We perform density functional theory calculations for the determination of the structural and electronic properties of epitaxial graphene on 4H-SiC(000 (1) over bar). Using commensurate supercells that minimize nonphysical stresses we show that in contrast with Si-face epitaxial films, the first graphene layer that forms on the C-face of SiC is purely metallic with its pi-bands partially preserved. Typical free-standing characteristics are fully recovered with a second graphene layer. We moreover discuss on the magnetic properties of the interface and the absence of Fermi-level pinning effects that could allow for a plausible device operation starting from the off-state.