Determinant Quantum Monte Carlo Study of the Orbitally Selective Mott Transition

TL;DR

This study uses determinant Quantum Monte Carlo to investigate an orbitally selective Mott transition in a two-band Hubbard model, revealing that the weakly interacting band remains metallic while the other localizes, and highlighting the role of magnetic order.

Contribution

It demonstrates the occurrence of an orbitally selective Mott transition using DQMC and tests the validity of the momentum independent self-energy approximation in this context.

Findings

Weakly interacting band remains metallic during OSMT

Long range antiferromagnetic order develops in the insulating phase

Critical interaction strengths are below the bandwidth of the itinerant orbital

Abstract

We study the conductivity, density of states, and magnetic correlations of a two dimensional, two band fermion Hubbard model using determinant Quantum Monte Carlo (DQMC) simulations. We show that an orbitally selective Mott transition (OSMT) occurs in which the more weakly interacting band can be metallic despite complete localization of the strongly interacting band. The DQMC method allows us to test the validity of the use of a momentum independent self-energy which has been a central approximation in previous OSMT studies. In addition, we show that long range antiferromagnetic order (LRAFO) is established in the insulating phase, similar to the single band, square lattice Hubbard Hamiltonian. Because the critical interaction strengths for the onset of insulating behavior are much less than the bandwidth of the itinerant orbital, we suggest that the development of LRAFO plays a key role in the transitions.