Berlin 2018 – scientific programme
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O: Fachverband Oberflächenphysik
O 27: Graphene: Electronic properties, structure and substrate interaction II (joint session O/TT)
O 27.9: Talk
Tuesday, March 13, 2018, 12:45–13:00, MA 043
Origin of the band gap in Bi-intercalated graphene on Ir(111) — •Maxim Krivenkov1,2, Dmitry Marchenko1, Evangelos Golias1, Jaime Sánchez-Barriga1, Oliver Rader1, and Andrei Varykhalov1 — 1Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, D-12489 Berlin, Germany — 2Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Str. 24/25, 14476 Potsdam, Germany
We report a study of the structural and electronic properties of epitaxial graphene on Ir(111) intercalated with Bi. A novel structural phase of intercalated Bi was observed which is remarkably different from the phase reported earlier by Warmuth et al. [1]. This novel phase is more dense and, as seen by angle resolved photoemission spectroscopy, provides a quasifreestanding graphene with a very small band gap (∼180 meV) and nearly ideal band structure without band replicas and electronic hybridization with the substrate. Furthermore, we demonstrate the possibility of fine tuning (±30 meV) of the band gap width in the Dirac cone by varying concentration of Bi.
To determine a possible origin of the observed band gap in Dirac point, we analyze the effect of structural corrugation on graphene band structure as well as interference effects in photoemission from graphene. The band gap was concluded to be of trivial nature and is ascribed to the breaking of sublattice symmetry of graphene.
[1] Warmuth et al. in Phys. Rev. B 93, 165437 (2016)