The ground state phase diagram of the half-filled repulsive Hubbard model in a bilayer is investigated using cluster dynamical mean field theory. For weak to intermediate values of Coulomb repulsion U, the system undergoes a transition from a Mott insulating phase to a metallic phase and then onto a band insulating phase as the interlayer hopping is increased. In the strong coupling case, the model exhibits a direct crossover from a Mott insulating phase to a band insulating phase. These results are robust with respect to the presence or absence of magnetic order.
@article{arxiv.cond-mat/0703728,
title = {Band insulator to Mott insulator transition in a bilayer Hubbard model},
author = {S. S. Kancharla and S. Okamoto},
journal= {arXiv preprint arXiv:cond-mat/0703728},
year = {2009}
}