Competing insulating phases of dipolar bosons in a dimerized optical lattice

We study the ground state properties of dipolar bosons in a one dimensional dimerized optical lattice. In the limit of strong onsite repulsion i.e. hardcore bosons, and strong dipole-dipole interaction, a stable density wave (DW) phase is obtained at half filling as a function of lattice dimerization. Interestingly, at quarter filling we obtain the signatures of an insulating phase which has both the character the bond-order (BO) and the DW insulators which we call a bond-order density wave (BODW) phase. Moreover, we show that for a fixed hopping dimerization there occurs a BO-DW phase crossover as a function of the dipole-dipole interaction and the BODW phase is more robust when the hopping dimerization is stronger. We further examine the stability of the BODW phase in the limit of finite onsite interactions.