Spin, charge and orbital fluctuations in a multi-orbital Mott insulator

TL;DR

This study investigates how spin, charge, and orbital fluctuations influence the Mott transition in a two-orbital Hubbard model, revealing hybridization-induced orbital fluctuations and Kondo-like heavy-fermion behavior.

Contribution

It combines dynamical mean-field theory with quantum Monte Carlo to analyze the impact of orbital hybridization on fluctuations near the Mott transition.

Findings

Orbital fluctuations are enhanced by hybridization.

Hybridization leads to Kondo-like heavy-fermion behavior.

Temperature dependence of susceptibilities elucidates the Mott transition.

Abstract

The two-orbital degenerate Hubbard model with distinct hopping integrals is studied by combining dynamical mean-field theory with quantum Monte Carlo simulations. The role of orbital fluctuations for the nature of the Mott transition is elucidated by examining the temperature dependence of spin, charge and orbital susceptibilities as well as the one-particle spectral function. We also consider the effect of the hybridization between the two orbitals, which is important particularly close to the Mott transition points. The introduction of the hybridization induces orbital fluctuations, resulting in the formation of a Kondo-like heavy-fermion behavior, similarly to $f$ electron systems, but involving electrons in bands of comparable width.