Extended Drude model and role of interband transitions in the mid-infrared spectra of pnictides

TL;DR

This paper demonstrates that interband transitions significantly influence the mid-infrared spectra of pnictides, challenging the validity of the extended-Drude model unless interband effects are properly subtracted.

Contribution

It provides a detailed analysis showing the importance of interband transitions in interpreting optical spectra of pnictides, highlighting limitations of the extended-Drude model.

Findings

Interband transitions contribute notably in the infrared spectra.

Extended-Drude model fails without subtracting interband effects.

First-principle calculations confirm the significance of interband processes.

Abstract

We analyze the outcomes of an extended-Drude-model approach to the optical spectra of pnictides, where the multiband nature of the electronic excitations requires a careful analysis of the role of interband processes in the optical conductivity.Through a direct comparison between model calculations of the intraband optical spectra and experimental data, we show that interband transitions,whose relevance is shown by first-principle calculations,give a non negligible contribution already in the infrared region. This leads to a substantial failure of the extended-Drude-model analysis on the measured optical data without subtraction of interband contributions.