Superfluidity and Density Order in a Bilayer Extended Hubbard Model

TL;DR

This study uses advanced computational methods to explore how interlayer interactions in a bilayer Hubbard model can induce superfluidity and density order, revealing novel pairing mechanisms without intralayer interactions.

Contribution

It demonstrates that interlayer interactions can induce superfluid and density-ordered phases, including a superfluid phase driven solely by density fluctuations, a novel finding.

Findings

Interlayer attraction induces checkerboard density order.

Superfluid phases with interlayer or intralayer pairing are observed.

Intralayer pairing can be induced without intralayer interactions.

Abstract

We use cluster dynamical mean field theory to study the phase diagram of the square lattice bilayer Hubbard model with an interlayer interaction. The layers are populated by two-component fermions, and the densities in both layers and the strength of the interactions are varied. We find that an attractive interlayer interaction can induce a checkerboard density ordered phase and superfluid phases, with either interlayer or intralayer pairing. Remarkably, the latter phase does not require an intralayer interaction to be present: it can be attributed to an induced attractive interaction caused by density fluctuations in the other layer.