Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 73: Scanning Probe Methods II
O 73.8: Vortrag
Donnerstag, 3. April 2014, 12:15–12:30, WIL A317
STM imaging of HOPG: Tip geometry effects — •Gábor Mándi1, Gilberto Teobaldi2, and Krisztián Palotás1 — 1Budapest University of Technology and Economics, Department of Theoretical Physics, Budafoki út 8., H-1111 Budapest, Hungary — 2Stephenson Institute for Renewable Energy, and Surface Science Research Centre, Department of Chemistry, University of Liverpool, L69 3BX Liverpool, UK
Highly oriented pyrolytic graphite (HOPG) is an important substrate in technological applications, particularly in scanning tunneling microscopy (STM) calibration. Therefore, the proper interpretation of the experimentally observed STM image contrasts is very important [1]. Using a three-dimensional (3D) Wentzel-Kramers-Brillouin (WKB) tunneling model [2,3] combined with first principles electronic structure calculations, we demonstrate that the tip orientation has a considerable effect on the simulated STM images. We show that the local rotation of the apex of the STM tip can cause a triangular-hexagonal contrast change. By comparing STM topographic data between experiment [1] and large scale simulations, we can determine particular tip orientations that are most likely present in the STM experiment.
[1] G. Teobaldi et al., Phys. Rev. B 85, 085433 (2012).
[2] K. Palotás et al., Phys. Rev. B 86, 235415 (2012).
[3] G. Mándi et al., J. Phys.: Condens. Matter 25, 445009 (2013).