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Family behavior and Dirac bands in armchair nanoribbons with 4–8 defect lines

Roland Gillen Orcid Logo, Janina Maultzsch

Journal of Physics: Condensed Matter, Volume: 36, Issue: 29, Start page: 295501

Swansea University Author: Roland Gillen Orcid Logo

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Abstract

Bottom-up synthesis from molecular precursors is a powerful route for the creation of novel synthetic carbon-based low-dimensional materials, such as planar carbon lattices. The wealth of conceivable precursor molecules introduces a significant number of degrees-of-freedom for the design of material...

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Published in: Journal of Physics: Condensed Matter
ISSN: 0953-8984 1361-648X
Published: IOP Publishing 2024
Online Access: Check full text

URI: https://cronfa.swan.ac.uk/Record/cronfa66642
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Abstract: Bottom-up synthesis from molecular precursors is a powerful route for the creation of novel synthetic carbon-based low-dimensional materials, such as planar carbon lattices. The wealth of conceivable precursor molecules introduces a significant number of degrees-of-freedom for the design of materials with defined physical properties. In this context, a priori knowledge of the electronic, vibrational and optical properties provided by modern ab initio simulation methods can act as a valuable guide for the design of novel synthetic carbon-based building blocks. Using density functional theory, we performed simulations of the electronic properties of armchair-edged graphene nanoribbons (AGNR) with a bisecting 4–8 ring defect line. We show that the electronic structures of the defective nanoribbons of increasing width can be classified into three distinct families of semiconductors, similar to the case of pristine AGNR. In contrast to the latter, we find that every third nanoribbon is a zero-gap semiconductor with Dirac-type crossing of linear bands at the Fermi energy. By employing tight-binding models including interactions up to third-nearest neighbors, we show that the family behavior, the formation of direct and indirect band gaps and of linear band crossings in the defective nanoribbons is rooted in the electronic properties of the individual nanoribbon halves on either side of the defect lines, and can be effectively through introduction of additional 'interhalf' coupling terms.
Keywords: density functional theory, electronic properties, graphene nanoribbons, defects, Dirac bands
College: Faculty of Science and Engineering
Funders: The authors gratefully acknowledge the scientific support and HPC resources provided by the Erlangen National High Performance Computing Center (NHR@FAU) of the Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) uUnder the NHR Project b181dc. NHR funding is provided by federal and Bavarian state authorities. NHR@FAU hardware is partially funded by the German Research Foundation (DFG)- 440719683. This work was supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)- GRK2861- 491865171 and Project Number 182849149 (SFB 953, B13)
Issue: 29
Start Page: 295501