Band insulator to Mott insulator transition in a bilayer Hubbard model

TL;DR

This study explores the phase transitions in a bilayer Hubbard model, revealing how varying interlayer hopping and Coulomb repulsion induce transitions from Mott insulators to metals and band insulators, using cluster dynamical mean field theory.

Contribution

It provides a detailed phase diagram of the bilayer Hubbard model, highlighting the nature of insulator-metal-insulator transitions at different interaction strengths.

Findings

Weak to intermediate U: Mott insulator to metal to band insulator transition.

Strong U: Direct crossover from Mott insulator to band insulator.

Transitions are robust regardless of magnetic order presence.

Abstract

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.