Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 34: Focused Session: Epitaxial Graphene IV
O 34.8: Vortrag
Mittwoch, 25. März 2009, 12:45–13:00, SCH 251
Quasifreestanding graphene on metallic substrates: preparation, structure, properties (interchanged with O 34.7) — •A. Varykhalov1, A. Shikin2, J. Sanchez-Barriga1, E. Vescovo3, D. Marchenko2, A. Rybkin2, D. Usachov2, C. Biswas1, and O. Rader1 — 1HZB, BESSY-II, Berlin, Germany — 2St.-Petersburg State University, Russia — 3NSLS, USA
Quasifreestanding graphene was prepared by cracking of propylene on metallic Ni(111) and Co(0001) followed by intercalation of Au monolayer into the interface between graphene and its substrate. Structural properties of such graphene as well as intercalation kinetics were monitored by means of scanning tunneling microscopy and angle-resolved photoelectron spectroscopy. Our high-resolution photoemission study reveal quasiparticles in the vicinity of the Fermi level due to interaction between graphene and Au. We demonstrate that in quasifreestanding graphene on Au, that Dirac crossing energy and Fermi energy coincide meaning charge neutrality and electronic properties are identical to those of ideal graphene. Using spin-resolved photoemission we show that the π-band of graphene on Au is spin-split and spin-polarized according to the Rashba model. Photoemission measurements allow us to conclude that hybridization between graphene band and spin-orbit split electronic states in high-Z material Au is responsible for the observed spin-polarization. Results are compared to the case of graphene on light material Cu where no spin-polarization and no interfacial hybridization were evidenced. Additionally we emphasize the protective role of graphene showing the band structure of graphene/Au/Ni(111) sampled before and after exposure to atmosphere.