Interplay of Mott Transition and Ferromagnetism in the Orbitally Degenerate Hubbard Model

TL;DR

This paper investigates how Mott transition and ferromagnetism interact in the orbitally degenerate Hubbard model, revealing the effects of band degeneracy and Hund's coupling on magnetic and insulating behaviors.

Contribution

It introduces a slave boson approach to analyze the degenerate Hubbard model and explores how degeneracy and Hund's rule coupling influence phase transitions and magnetic properties.

Findings

Metal-insulator transition weakly depends on degeneracy M.

Hubbard sub-band weights strongly depend on M.

Sizable Hund's coupling is necessary for ferromagnetic instability.

Abstract

A slave boson representation for the degenerate Hubbard model is introduced. The location of the metal to insulator transition that occurs at commensurate densities is shown to depend weakly on the band degeneracy M. The relative weights of the Hubbard sub-bands depend strongly on M, as well as the magnetic properties. It is also shown that a sizable Hund's rule coupling is required in order to have a ferromagnetic instability appearing. The metal to insulator transition driven by an increase in temperature is a strong function of it.