Berlin 2015 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 72: Low-Dimensional Systems: Poster Session

TT 72.20: Poster

Mittwoch, 18. März 2015, 15:00–18:00, Poster B

Electronic Instabilities of the AA-Honeycomb Bilayer — •David Sánchez de la Peña¹, Michael Scherer², and Carsten Honerkamp¹ — ¹Institute for Theoretical Solid State Physics, RWTH Aachen University, D-52056 Aachen, Germany and JARA Fundamentals of Future Information Technologies — ²Institute for Theoretical Physics, University of Heidelberg, D-69120 Heidelberg, Germany

We use a functional renormalization group approach to study the instabilities due to electron-electron interactions in a bilayer honeycomb lattice model with AA stacking, as it might be relevant for layered graphene with this structure. Starting with a tight-binding description for the four π-bands, modes of the dispersion are integrated out by successively lowering an infrared cutoff. For a given set of short-ranged interactions, the method allows for an unbiased investigation of the competing instabilities arising in the effective low-energy theory, and for the determination of the leading tendencies. The antiferromagnetic spin-density wave is an expected instability for dominant local repulsion among the electrons, but for nonlocal interaction terms also other instabilities occur. The resulting phase diagrams depending on the model parameters are presented. We compare our results to single-layer graphene and the more common AB-stacked bilayer, both qualitatively and quantitatively. Current prospects for the analysis of graphene systems using some of the latest developments in renormalization group methods are also discussed.