Dresden 2011 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 98: Graphene VI
O 98.5: Vortrag
Freitag, 18. März 2011, 12:15–12:30, WIL A317
Edge state on graphene probed by scanning tunneling spectroscopy — •Dinesh Subramaniam1, Christian Pauly1, Viktor Geringer1, Rafael Reiter2, Marco Pratzer1, Marcus Liebmann1, Yan Li4, Carsten Busse3, Riccardo Mazzarello4, Florian Libisch2, Thomas Michely3, and Markus Morgenstern1 — 1II. Physikalisches Institut B, RWTH Aachen University and JARA-FIT, Germany — 2Institut für theoretische Physik, Technische Universität Wien, Austria — 3II. Physikalisches Institut, Universität zu Köln, Germany — 4Institute for Theoretical Solid State Physics, RWTH Aachen University, Germany
Epitaxial graphene islands are prepared by ethylene deposition on Ir(111) at room temperature and subsequent annealing to 1050°C. The lateral dimension of the islands varies from 5 nm to 40 nm always showing zigzag edges. Atomic resolution STM images show singly saturated zigzag edges which are predicted to feature a spinpolarized state. Scanning tunneling spectroscopy (STS) measurements at the graphene edge partly show a pronounced peak at the Fermi level. Reference STS measurements on the iridium surface reveal a similar peak with lower intensity at the Fermi level, which could be identified as an iridium surface state. This suggests that the increase in intensity at the edge of the graphene is due to a coupling of the edge state to the iridium surface state which enhanced strongly the intensity of the peak. Recent DFT band structure calculation support this assumption. Spin-polarized STS has been performed using a bulk chrome tip in order to analyze the magnetic character of the edge state.