Bilayer Hubbard model for 3He: a cluster dynamical mean-field calculation

TL;DR

This paper models bilayer 3He using a Hubbard model on a triangular lattice, revealing a band-selective Mott transition and a first-order transition where the first layer fermions become localized and form spin singlets.

Contribution

It introduces a cluster dynamical mean-field approach to study bilayer 3He, identifying a Mott transition and spin singlet formation in a novel bilayer Hubbard model.

Findings

Observation of a band-selective Mott transition at critical chemical potential

First-order transition with fermion localization and spin singlet formation

Effective mass growth is truncated by the transition

Abstract

Inspired by recent experiments on bilayer 3He, we consider a bilayer Hubbard model on a triangular lattice. For appropriate model parameters, we observe a band-selective Mott transition at a critical chemical potential, mu_c, corresponding to the solidification of the fermions in the first layer. The growth of the effective mass on the metallic side (mu < mu_c) is cut off by a first order transition in which the first layer fermions drop out of the Luttinger volume and their spin degrees of freedom become locked in a spin singlet state. These results are obtained from a cluster dynamical mean-field calculation on an eight-site cluster with a quantum Monte Carlo cluster solver.