Mott transitions in the multi-orbital systems

TL;DR

This paper studies how electrons localize in multi-orbital systems, revealing that different orbitals undergo Mott transitions at distinct interaction strengths, influenced by Hund coupling components, using advanced theoretical methods.

Contribution

It demonstrates that separate Mott transitions in multi-orbital systems can occur at different Coulomb interactions and highlights the role of Hund coupling in this process.

Findings

Separate Mott transitions occur at different interaction strengths.

Hund coupling components influence the nature of the transitions.

Transitions merge into a single one under specific conditions.

Abstract

We investigate the Mott transitions in the two-orbital Hubbard model with different bandwidths. By combining dynamical mean field theory with the exact diagonalization, we discuss the stability of itinerant quasi-particle states in each band. We demonstrate that separate Mott transitions occur at different Coulomb interaction strengths in general, which merge to a single transition only under special conditions. In particular, it is clarified that the $xy$ and pair-hopping components of the Hund coupling play a key role to control the nature of the Mott transitions.