Metal-insulator transition in the two-orbital Hubbard model at fractional band fillings: Self-energy functional approach

TL;DR

This study explores the metal-insulator transition in a two-orbital Hubbard model at various fillings using the self-energy functional approach, revealing conditions for Mott insulating and orbital selective phases.

Contribution

It introduces a detailed analysis of the stability of metallic and insulating phases at fractional fillings in a two-orbital Hubbard model with different bandwidths.

Findings

Mott insulating phases occur at commensurate fillings.

Orbital selective Mott phase is stabilized at fractional fillings.

Different bandwidths influence phase stability.

Abstract

We investigate the infinite-dimensional two-orbital Hubbard model at arbitrary band fillings. By means of the self-energy functional approach, we discuss the stability of the metallic state in the systems with same and different bandwidths. It is found that the Mott insulating phases are realized at commensurate band fillings. Furthermore, it is clarified that the orbital selective Mott phase with one orbital localized and the other itinerant is stabilized even at fractional band fillings in the system with different bandwidths.