Quantum Monte Carlo study of bilayer ionic Hubbard model

The interaction-driven insulator-to-metal transition has been reported in the ionic Hubbard model (IHM) for intermediate interaction $U$, which poses fundamental interest in the correlated electronic systems. Here we use determinant quantum Monte Carlo to study the interplay of interlayer hybridization $V$ and two types of intralayer staggered potentials: one with the same (in-phase) and the other with a $\pi$-phase shift (anti-phase) potential in two layers termed as ``bilayer ionic Hubbard model''. We demonstrate that the interaction-driven Insulator-Metal transition extends to bilayer IHM with finite $V$ for both types of staggered potentials. Besides, the system with in-phase potential is prone to metallic phase with turning on interlayer hybridization while that with anti-phase potential tends to insulators with stronger charge density order.