Wednesday, April 17, 2013

1304.4576 (A. M. Rojas-Cuervo et al.)

Asymmetric Dirac cones in monatomic hexagonal lattices    [PDF]

A. M. Rojas-Cuervo, R. R. Rey-González
The study of nanostructures has contributed to the advance of an interdisciplinary science as nanotechnology is. Among those ones, graphene has been distinguished in the last years by its interesting properties and specially, in our own interest, the presence of Dirac cones in electronic dispersion relation. This material is considered the cornerstone in further scientific and technological innovation. In this theoretical paper, crystallographic phase systems similar to graphene, such as silicon hexagonal monolayer (h-Si) or germanium (h-Ge), are analyzed, using the density functional theory (DFT), implemented in the code SIESTA, in the generalized gradient approximation (GGA), into the Perdew-Burke-Ernzerhof functional (PBE) and optimized norm-conserving pseudopotentials. The results found permit us to report the chemical stability of h-Ge. Also, the lattice parameters, electronic dispersion relations and the density of states (DOS) for graphene, h-Si and h-Ge are reported. The existence of Dirac cones is seen in the electronic dispersion relation for each one of the studied hexagonal monolayers. The cones show lateral asymmetry in function of the direction around the $K$ point. In particular, Fermi velocities are calculated for holes and electrons in function of the direction.
View original: http://arxiv.org/abs/1304.4576

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