title: Epitaxial graphene on SiC(0001): more than just honeycombs.
abstract: Using scanning tunneling microscopy with Fe-coated W tips and first-principles calculations, we show that the interface of epitaxial graphene/SiC(0001) is a warped graphene layer with hexagon-pentagon-heptagon (H(5,6,7)) defects that break the honeycomb symmetry, thereby inducing a gap and states below E(F near the K point. Although the next graphene layer assumes the perfect honeycomb lattice, its interaction with the warped layer modifies )the dispersion about the Dirac point. These results explain recent angle-resolved photoemission and carbon core-level shift data and solve the long-standing problem of the interfacial structure of epitaxial graphene on SiC(0001).
authors.affiliation: Department of Physics and Laboratory for Surface Studies, University of Wisconsin, Milwaukee, Wisconsin 53211, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Qi
authors.forename: S H
authors.initials: SH
authors.lastname: Rhim
authors.forename: G F
authors.initials: GF
authors.lastname: Sun
authors.forename: M
authors.initials: M
authors.lastname: Weinert
authors.forename: L
authors.initials: L
authors.lastname: Li