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TT: Fachverband Tiefe Temperaturen

TT 50: Correlated Electrons: Quantum-Critical Phenomena - Theory

TT 50.3: Vortrag

Dienstag, 1. April 2014, 14:30–14:45, BEY 81

Excitonic Instability at Spin-State Transition — •Jan Kuneš and Pavel Augustinský — Institute of Physics, ASCR, Prague, Czechia

We report a newly observed instability of the half-filled two-band Hubbard model in the vicinity of the spin-state transition. [1] Using dynamical mean-field theory we have performed a unbiased search for divergent particle-hole susceptibilities. Depending on the bandwidths ratio the system was found to establish a checker-board order of high- and low-spin sites, breaking the discrete translational symmetry, or to undergo a condensation of spinful excitons, breaking a continuous gauge symmetry. Besides numerical results we provide an analytic description in the strong-coupling limit where the problem maps of a variate of the bosonic t-J model.
Kunes and Augustinsky, arXiv:1310.0669