Contrast stability and ‘stripe’ formation in scanning tunnelling microscopy imaging of highly oriented pyrolytic graphite: the role of STM-tip orientations



Mándi, Gábor, Teobaldi, Gilberto ORCID: 0000-0001-6068-6786 and Palotás, Krisztián
(2014) Contrast stability and ‘stripe’ formation in scanning tunnelling microscopy imaging of highly oriented pyrolytic graphite: the role of STM-tip orientations. Journal of Physics: Condensed Matter, 26 (48). p. 485007.

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Abstract

Highly oriented pyrolytic graphite (HOPG) is an important substrate in many technological applications and is routinely used as a standard in Scanning Tunnelling Microscopy (STM) calibration, which makes the accurate interpretation of the HOPG STM contrast of great fundamental and applicative importance. We demonstrate by STM simulations based on electronic structure obtained from first principles that the relative local orientation of the STM-tip apex with respect to the HOPG substrate has a considerable effect on the HOPG STM contrast. Importantly for experimental STM analysis of HOPG, the simulations indicate that local tip-rotations maintaining a major contribution of the d_{3z2-r2} tip-apex state to the STM current affect only the secondary features of the HOPG STM contrast resulting in 'stripe' formation and leaving the primary contrast unaltered. Conversely, tip-rotations leading to enhanced contributions from m ≠ 0 tip-apex electronic states can cause a triangular-hexagonal change in the primary contrast. We also report a comparison of two STM simulation models with experiments in terms of bias-voltage-dependent STM topography brightness correlations and discuss our findings for the HOPG(0 0 0 1) surface in combination with tungsten tip models of different sharpnesses and terminations.

Item Type: Article
Additional Information: Published 29 October 2014.
Subjects: ?? QC ??
Depositing User: Symplectic Admin
Date Deposited: 05 Aug 2015 08:35
Last Modified: 16 Dec 2022 12:06
DOI: 10.1088/0953-8984/26/48/485007
Publisher's Statement : This is an author-created, un-copyedited version of an article accepted for publication in Journal of Physics: Condensed Matter. The publisher is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at http://dx.doi.org/10.1088/0953-8984/26/48/485007 .
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URI: https://livrepository.liverpool.ac.uk/id/eprint/2018920

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