Regensburg 2013 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 30: Correlated Electrons: Quantum Impurities, Kondo Physics

TT 30.13: Talk

Tuesday, March 12, 2013, 12:45–13:00, H21

Interaction-driven transition between topological states in a Kondo insulator — •Jan Werner and Fakher Assaad — Theoretische Physik 1, Universität Würzburg, Deutschland

Heavy fermion materials naturally combine strong spin-orbit interactions and electronic correlations. When there is precisely one conduction electron per impurity spin, the coherent heavy fermion state is insulating. This Kondo insulating state has recently been argued to belong to the class of quantum spin Hall states [1]. Motivated by this conjecture and a very recent experimental realisation of this state[2], we investigate a model for Kondo insulators with spin-orbit coupling. Using DMFT, we observe an interaction-driven transition between two distinct topological states, indicated by a closing of the bulk gap and a simultaneous change of the Z₂ topological invariant. Upon reopening of the bulk gap the system remains a topological insulator, however with a zero energy edge mode now at the X-point instead of the Gamma-point.
[1] M. Dzero, K. Sun, P. Coleman, and V. Galitski, Phys. Rev. B 85, 045130 (2012)
S. Wolgast et. al., arXiv:1211.5104 (2012)