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arXiv · 1707.00339

Singlet exciton condensation and bond-order-wave phase in the extended Hubbard model

Mohsen Hafez-Torbati·Götz S. Uhrig
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Abstract

The competition of interactions implies the compensation of standard mechanisms which leads to the emergence of exotic phases between conventional phases. The extended Hubbard model (EHM) is a fundamental example for the competition of the local Hubbard interaction and the nearest-neighbor density-density interaction, which at half-filling and in one dimension leads to a bond order wave (BOW) between a charge density wave (CDW) and a quasi-long-range order Mott insulator (MI). We study the full momentum-resolved excitation spectrum of the one dimensional EHM in the CDW phase and clarify the relation between different elementary energy gaps. We show that the CDW-to-BOW transition is driven by the softening of a singlet exciton at momentum $π$. The BOW is realized as the condensate of this singlet exciton.

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Mohsen Hafez-Torbati, Götz S. Uhrig. 2017-09-26. Singlet exciton condensation and bond-order-wave phase in the extended Hubbard model. https://doi.org/10.1103/physrevb.96.125129

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