Mott-Hubbard transition in the mass-imbalanced Hubbard model

TL;DR

This paper investigates the metal-insulator transition in the mass-imbalanced Hubbard model using dynamical mean field theory, revealing that even slight mobility differences lead to a transition similar to the Hubbard model, with a first-order transition at low temperatures.

Contribution

It demonstrates that the metal-insulator transition in the mass-imbalanced Hubbard model closely resembles that of the Hubbard model when a small hopping is introduced, highlighting the transition's nature.

Findings

First-order metal-insulator transition at low temperatures.

Central peak width is consistent for both fermion types near transition.

Transition behavior aligns with the Hubbard model even with mass imbalance.

Abstract

The mass-imbalanced Hubbard model represents a continuous evolution from the Hubbard to the Falicov-Kimball model. We employ dynamical mean field theory and study the paramagnetic metal-insulator transition, which has a very different nature for the two limiting models. Our results indicate that the metal-insulator transition rather resembles that of the Hubbard model as soon as a tiny hopping between the more localized fermions is switched on. At low temperatures we observe a first-order metal-insulator transition and a three peak structure. The width of the central peak is the same for the more and less mobile fermions when approaching the phase transition, which agrees with our expectation of a common Kondo temperature and phase transition for the two species.