Electron-boson spectral density function of correlated multiband systems obtained from optical data: Ba0.6K0.4Fe2As2 and LiFeAs

TL;DR

This paper presents a new approximate method to extract electron-boson spectral density functions from optical data in multiband superconductors, applied to pnictides, revealing features similar to cuprates and aiding understanding of strong correlations.

Contribution

The paper introduces an approximate reverse analysis method for optical conductivity data in multiband systems, enabling extraction of electron-boson spectral densities.

Findings

Spectral densities show a sharp mode and broad background.

Multiband spectral densities resemble those of cuprates.

Method helps explore strong correlations in pnictide superconductors.

Abstract

We introduce an approximate method which can be used to simulate the optical conductivity data of correlated multiband systems for normal and superconducting cases by taking advantage of a reverse process of a usual optical data analysis, which has been used to extract the electron-boson spectral density function from measured optical spectra of single-band systems, like cuprates. We applied this method to optical conductivity data of two multiband pnictide systems (Ba0.6K0.4Fe2As2 and LiFeAs) and obtained the electron-boson spectral density functions. The obtained electron-boson spectral density consists of a sharp mode and a broad background. The obtained spectral density functions of the multiband systems show similar properties as those of cuprates in several aspects. We expect that our method helps to reveal the nature of strong correlations in the multiband pnictide superconductors.