Emergence of a common energy scale close to the orbital-selective Mott transition

TL;DR

This paper uses dynamical mean-field theory to show that near the orbital-selective Mott transition, a common energy scale emerges in multi-band Hubbard models with strong Hund's coupling, linking spin dynamics and spectral features.

Contribution

It reveals the emergence of a shared energy scale near the transition, explained via a Kondo-type model, highlighting the role of local spin dynamics in multi-band systems.

Findings

A common energy scale appears near the orbital-selective Mott transition.

Strong Hund's coupling is essential for the emergence of this energy scale.

Spin dynamics, not spectral functions, determine the kink locations in the band structure.

Abstract

We calculate the spectra and spin susceptibilities of a Hubbard model with two bands having different bandwidths but the same on-site interaction, with parameters close to the orbital-selective Mott transition, using dynamical mean-field theory. If the Hund's rule coupling is sufficiently strong, one common energy scale emerges which characterizes both the location of kinks in the self-energy and extrema of the diagonal spin susceptibilities. A physical explanation of this energy scale is derived from a Kondo-type model. We infer that for multi-band systems local spin dynamics rather than spectral functions determine the location of kinks in the effective band structure.