Extracting the electron--boson spectral function $\alpha^2$F($\omega$) from infrared and photoemission data using inverse theory

TL;DR

This paper introduces a novel inverse theory-based method to accurately extract the electron-boson spectral function from infrared and photoemission data, improving analysis of high-temperature superconductor spectra.

Contribution

A new inverse theory approach for extracting $oldsymbol{ ext{alpha}^2 ext{F}(oldsymbol{ extomega})}$ from experimental data, with detailed numerical implementation and comparison to existing methods.

Findings

Successfully determines doping and temperature dependence of spectral functions.

Reveals resonance structures consistent with theoretical models.

Highlights limitations of current extraction techniques.

Abstract

We present a new method of extracting electron-boson spectral function $\alpha^2$F($\omega$) from infrared and photoemission data. This procedure is based on inverse theory and will be shown to be superior to previous techniques. Numerical implementation of the algorithm is presented in detail and then used to accurately determine the doping and temperature dependence of the spectral function in several families of high-T$_c$ superconductors. Principal limitations of extracting $\alpha^2$F($\omega$) from experimental data will be pointed out. We directly compare the IR and ARPES $\alpha^2$F($\omega$) and discuss the resonance structure in the spectra in terms of existing theoretical models.