Dresden 2011 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 1: TR: Graphene 1 (jointly with MA, HL, and DY)

TT 1.4: Talk

Monday, March 14, 2011, 11:30–11:45, HSZ 03

Graphene Superlattices Studied by Ab-Initio Methods — •Lars Matthes, Karsten Hannewald, Jürgen Furthmüller, and Friedhelm Bechstedt — Institut für Festkörpertheorie und -optik, Friedrich-Schiller-Universität, Jena, Germany

The peculiar electronic properties of graphene have stimulated extensive research towards graphene-based electronics. Hereby, of particular interest are quasi-1D structures such as graphene nanoribbons [1] or, more recently, graphene superlattices [2] which allow a systematic tuning of the band structure. An impressive example for such modifications has been predicted by recent Kronig-Penney-type calculations [2] for a single graphene layer subject to a 1D periodic potential where a rather counterintuitive anisotropic renormalization of the Fermi velocity due to the Klein paradox is expected. Here, we present first-principles DFT calculations of graphene superlattices using the VASP code. The influence of the periodic external potential on the charge-carrier redistribution and corresponding screening effects is investigated in detail. The resulting consequences for the ab-initio band structure including anisotropy effects are studied and compared with analytical calculations based on the Dirac Hamiltonian. Deviations due to self-consistent inclusion of screening effects and nonlinear dispersions are analyzed. Finally, consequences for the practical realization of graphene superlattices with 1D transport properties are discussed.
See, e.g., U. Treske, F. Ortmann, B. Oetzel, K. Hannewald, F. Bechstedt, phys. stat. sol. (a) 207, 304 (2010)
C-H. Park et al., Nature Phys. 4, 213 (2008)