Mott transitions in two-orbital Hubbard systems

TL;DR

This paper explores the nature of Mott transitions in two-orbital Hubbard models, revealing conditions for separate or unified transitions and examining effects like hybridization and heavy fermion states.

Contribution

It introduces a detailed analysis of orbital-dependent Mott transitions using dynamical mean field theory, highlighting conditions for single versus multiple transitions.

Findings

Separate Mott transitions occur at different Coulomb interactions.

Special interaction conditions lead to a unified Mott transition.

Hybridization induces Kondo-like heavy fermion states.

Abstract

We investigate the Mott transitions in two-orbital Hubbard systems. Applying the dynamical mean field theory and the self-energy functional approach, we discuss the stability of itinerant quasi-particle states in each band. It is shown that separate Mott transitions occur at different Coulomb interaction strengths in general. On the other hand, if some special conditions are satisfied for the interactions, spin and orbital fluctuations are equally enhanced at low temperatures, resulting in a single Mott transition. The phase diagrams are obtained at zero and finite temperatures. We also address the effect of the hybridization between two orbitals, which induces the Kondo-like heavy fermion states in the intermediate orbital-selective Mott phase.