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Graphene with vacancies: Supernumerary zero modes
Article
Weik, Norman, Schindler, Johannes, Bera, Soumya, Solomon, Gemma C. and Evers, Ferdinand
(2016)
Graphene with vacancies: Supernumerary zero modes.
Physical Review B 94 (6), 064204.
DOI to cite this document: 10.5283/epub.46098
Abstract
The density of states ϱ(E) of graphene is investigated within the tight-binding (Hückel) approximation in the presence of vacancies. They introduce a nonvanishing density of zero modes nzm that act as midgap states, ϱ(E)=nzmδ(E)+smooth. As is well known, the actual number of zero modes per sample can, in principle, exceed the sublattice imbalance, Nzm≥∣∣NA−NB∣∣, where NA,NB denote the number of ...
The density of states ϱ(E) of graphene is investigated within the tight-binding (Hückel) approximation in the presence of vacancies. They introduce a nonvanishing density of zero modes nzm that act as midgap states, ϱ(E)=nzmδ(E)+smooth. As is well known, the actual number of zero modes per sample can, in principle, exceed the sublattice imbalance, Nzm≥∣∣NA−NB∣∣, where NA,NB denote the number of carbon atoms in each sublattice. In this paper, we establish a stronger relation that is valid in the thermodynamic limit and that involves the concentration of zero modes, nzm>∣∣cA−cB∣∣, where cA and cB denote the concentration of vacancies per sublattice; in particular, nzm is nonvanishing even in the case of balanced disorder, NA/NB=1. Adopting terminology from benzoid graph theory, the excess modes associated with the current carrying backbone (percolation cluster) are called supernumerary. In the simplest cases, such modes can be associated with structural elements such as carbon atoms connected with a single bond, only. Our result suggests that the continuum limit of bipartite hopping models supports nontrivial “supernumerary” terms that escape the present continuum descriptions.
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| Item type | Article | ||||
| Journal or Publication Title | Physical Review B | ||||
| Publisher | American Physical Society (APS) | ||||
| Open Access Type | Due to SHERPA/RoMEO | ||||
| Volume | 94 | ||||
| Number of Issue or Book Chapter | 6 | ||||
| Page Range | 064204 | ||||
| Date | 26 August 2016 | ||||
| Date of publication | 25 Jun 2021 05:26 | ||||
| Institutions | Physics > Institute of Theroretical Physics > Chair Ferdinand Evers | ||||
| Identification Number |
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| Dewey Decimal Classification | 500 Science > 530 Physics | ||||
| Status | Published | ||||
| Refereed | Yes, this version has been refereed | ||||
| Created at the University of Regensburg | Partially | ||||
| URN of the UB Regensburg | urn:nbn:de:bvb:355-epub-460981 | ||||
| Item ID | 46098 |
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