paper

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

arXiv:1707.00339 · doi:10.1103/PhysRevB.96.125129

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 . The BOW is realized as the condensate of this singlet exciton.

6 pages, 3 figures

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