Regensburg 2010 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 8: CE: (General) Theory
TT 8.4: Talk
Monday, March 22, 2010, 14:45–15:00, H21
Instabilities of quadratic band crossing points — •Stefan Uebelacker1 and Carsten Honerkamp2 — 1University of Würzburg — 2RWTH Aachen
The variation of the orbital composition of bands around band crossing points near the Fermi level can generate interesting effects. In particular, rather simple interactions can give rise to the spontaneous formation of topological insulating phases (S. Raghu et al., Phys. Rev. Lett. 100, 156401 (2008)). In contrast with Dirac points, quadratic band crossing points offer the advantage of a nonzero density of states at the crossing point, and instabilities occur already at small interaction strengths. Here, we present our results of functional renormalization group calculations for models with one and two quadratic band crossing points and discuss the possibilities for nontrivial insulating phases induced by local interactions.