S. Barkhofen, M. Bellec, U. Kuhl, F. Mortessagne
Experiments on hexagonal graphene-like structures using microwave measuring techniques are presented. The lowest coupled transverse-electric resonance of coupled dielectric discs sandwiched between two metallic plates establish a tight-binding configuration baring a lot of opportunities realising different lattice structures. In measurements on graphene-like sheets the vanishing density of states at the Dirac point is observed as well as the linear slope close to it. As the position of the excitation by the microwave antenna is possible at any place of the 'graphene' flake, edge states were detected at zigzag edges or corners of the lattice and not found in the interior of the sheet or at an armchair edge in agreement with theoretical predictions. Taking advantage of the high flexibility of the disc position, consequences of introduced disorder on the band structures are investigated. By using different kind of discs an imitation of boron nitride - a hexagonal crystal consisting of two different sorts of atoms - is implemented showing a band gap in the band structure.
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http://arxiv.org/abs/1205.5488
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