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(0001). 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 π-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.