Bands, resonances, edge singularities and excitons in core level spectroscopy investigated within the dynamical mean field theory

TL;DR

This paper demonstrates how dynamical mean field theory effectively models complex spectral features like band excitations, resonances, and excitons in core level spectroscopy, providing insights into correlated electron systems.

Contribution

It introduces a new impurity solver within DMFT that captures detailed spectral phenomena in core level XAS and cPES, highlighting the evolution of quasiparticle peaks and the role of nonlocal screening.

Findings

XAS shows limited sensitivity to metal-insulator transition.

cPES can measure local charge fluctuations.

Core-valence interactions influence spectral resonance shapes.

Abstract

Using a recently developed impurity solver we exemplify how dynamical mean field theory captures band excitations, resonances, edge singularities and excitons in core level x-ray absorption (XAS) and core level photo electron spectroscopy (cPES) on metals, correlated metals and Mott insulators. Comparing XAS at different values of the core-valence interaction shows how the quasiparticle peak in the absence of core-valence interactions evolves into a resonance of similar shape, but different origin. Whereas XAS is rather insensitive to the metal insulator transition, cPES can be used, due to nonlocal screening, to measure the amount of local charge fluctuation.