Orbital-selective Mott transitions in the degenerate Hubbard model

TL;DR

This paper studies how different electronic bands in a two-band Hubbard model undergo Mott transitions at varying interaction strengths, revealing conditions for separate or unified transitions, with implications for ruthenate materials.

Contribution

It demonstrates the occurrence of orbital-selective Mott transitions in a two-band Hubbard model using dynamical mean field theory, highlighting conditions for their separation or merging.

Findings

Separate Mott transitions occur at different Coulomb interactions.

Transitions merge into a single one under specific conditions.

Relevance to the physics of Ca$_{2-x}$Sr$_x$RuO$_4$.

Abstract

We investigate the Mott transitions in two-band Hubbard models with different bandwidths. Applying dynamical mean field theory, 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. This kind of behavior may be relevant for the physics of the single-layer ruthenates, Ca$_{2-x}$Sr$_x$RuO$_4$.