Kink during the formation of the Kondo resonance band in the heavy fermion system

TL;DR

This study combines DFT and DMFT to analyze the formation of the Kondo resonance band in CeCoGe2, revealing kinks in spectral functions that relate to the temperature-dependent evolution of heavy fermion states.

Contribution

It provides a detailed theoretical analysis of the Kondo resonance formation and identifies spectral kinks associated with topological changes in band structure during cooling.

Findings

Dispersive Kondo resonance states observed at low temperature.

Kinks in spectral functions near the Fermi level linked to temperature scales.

Topological change in band shapes during the Kondo resonance formation.

Abstract

We have investigated the formation of the Kondo resonance (KR) band and the hybridization gap (HG) in the heavy fermion compound CeCoGe2, using a combined approach of the density functional theory (DFT) and the dynamical mean field theory (DMFT). Low temperature (T) spec-tral functions show dispersive KR states, similarly to the recent experimental observation. During the evolution from the nonf conduction band state at high T to the dispersive KR band state at low T, which have topologically different band shapes, we have found the existence of kinks in the spectral function near EF . The observation of kink is clearly in correspondence with the multiple temperature scale of the formation of the KR band. We suggest that the detailed analysis on the abrupt change of electron velocity and the scattering rate near the Fermi level will provide crucial information for the heavy fermion system.