Regensburg 2016 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 63: Low-Dimensional Systems: 2D - Theory

TT 63.5: Vortrag

Donnerstag, 10. März 2016, 10:30–10:45, H21

Nonlocal density interactions on the honeycomb and bilayer square lattice — •Stefan Wessel and Michael Golor — Institute for Theoretical Solid State Physics, RWTH Aachen University

We consider an efficient scheme to perform sign problem-free determinantal quantum Monte Carlo simulations of Hubbard models with non-local density-density interactions on half-filled bipartite lattices, based on a bond-decoupling of the extended interaction terms. We apply our scheme to the Hubbard model on the square lattice bilayer with an interlayer repulsion, and present the ground state phase diagram within the accessible parameter region. In particular, for sufficiently strong interlayer tunneling, we observe the emergence of a direct dimer product state of mixed D-Mott and S-Mott character. We also examine the stability range of this state within strong-coupling perturbation theory. Furthermore, we consider the Hubbard model on the honeycomb lattice with next-nearest-neighbor interactions. Such an interaction is found to enhance both charge density and spin-current correlations within the semimetallic region. However, inside the accessible parameter region, they do not stabilize long-ranged charge density wave order nor a quantum spin Hall state, and the only insulating state that we observe exhibits long-range antiferromagnetism.