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Fractional-filling Mott domains in two dimensional optical superlattices

Pierfrancesco Buonsante·Vittorio Penna·Alessandro Vezzani
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Abstract

Ultracold bosons in optical superlattices are expected to exhibit fractional-filling insulating phases for sufficiently large repulsive interactions. On strictly 1D systems, the exact mapping between hard-core bosons and free spinless fermions shows that any periodic modulation in the lattice parameters causes the presence of fractional-filling insulator domains. Here, we focus on two recently proposed realistic 2D structures where such mapping does not hold, i.e. the two-leg ladder and the trimerized kagome' lattice. Based on a cell strong-coupling perturbation technique, we provide quantitatively satisfactory phase diagrams for these structures, and give estimates for the occurrence of the fractional-filling insulator domains in terms of the inter-cell/intra-cell hopping amplitude ratio.

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Pierfrancesco Buonsante, Vittorio Penna, Alessandro Vezzani. 2005-05-26. Fractional-filling Mott domains in two dimensional optical superlattices. https://doi.org/10.1103/physreva.72.031602

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