Dresden 2011 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 9: Graphene II (organised by TT)
DY 9.10: Talk
Monday, March 14, 2011, 16:30–16:45, HSZ 304
Edge magnetism in nanoribbons of graphene — •Hélène Feldner1,2, Zi Yang Meng3, Thomas C. Lang4, Fakher Assaad4, Stefan Wessel3, Andreas Honecker2, and Daniel Cabra1 — 1IPCMS, Strasbourg, France — 2Institut für Theoretische Physik, Göttingen, Germany — 3Institut für Theoretische Physik III, Stuttgart, Germany — 4Institut für Theoretische Physik und Astrophysik, Würzburg Am Hubland, Germany
A simple tight-binding model is sufficient to describe most of graphene’s properties, but a Hubbard model is needed to account for its magnetic properties. To be able to compute quantities in direct space and for big systems of realistic size with chosen geometry, we use a mean field approximation solved in a self-consistent way in the direct space. In agreement with known results, we find a Mott-Hubbard transition, and a magnetization of the zig-zag edge of finite samples. We have studied the accuracy of the approximation by a comparison of our results with those obtained by exact diagonalization and quantum Monte-Carlo simulations [1]. The main point of our current work consists of a study of the graphene zig-zag ribbons by mean field and quantum Monte-Carlo simulations. First we have looked at the static magnetism of the zig-zag edges and in a second part the local spectral function. These quantities allow us to study the influence of static magnetism on dynamical properties and the local density of states which is a quantity accessible experimentally by STM and shows different behavior on the edge with and without magnetic properties.
Phys. Rev. B 81, 115416 (2010).