Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 34: Focused Session: Epitaxial Graphene IV
O 34.4: Vortrag
Mittwoch, 25. März 2009, 11:45–12:00, SCH 251
Manipulation of the electronic structure of graphene on Ir(111) — •Marko Kralj1, Ivo Pletikosić1, Petar Pervan1, Milorad Milun1, Alpha N’Diaye2, Carsten Busse2, and Thomas Michely2 — 1Institut za fiziku, Zagreb, Croatia — 2II. Physikalisches Institut, Köln, Germany
Epitaxial graphene on Ir(111) exhibits effects of the 2.5 nm moiré superperiodicity which is due to the mismatch of graphene and iridium lattices. Angle resolved photoelectron spectroscopy (ARPES) reveals intact Dirac cone, slight p-doping (0.1 eV) and opening of minigaps in the band structure of graphene due to the superperiodic potential of the order of 100 mV [1].
In this work, electronic doping of graphene by alkalis (Na, Cs, K) at varying concentrations shifted the position of the Dirac point up to 1.4 eV below the Fermi energy. Moreover, upon the intercalation of alkalis the effects of the superperiodicity vanished and the minigaps disappeared. In the (maximum doping) regime where graphene Fermi surface becomes pronouncedly trigonal, an anisotropic effect of the pi-band dispersion renormalization was clearly observed. We interpret this as a signature of an enhanced electron-phonon coupling in doped graphene.
[1] I. Pletikosić et al., arXiv:0807.2770.