Local interpretation of time-resolved x-ray absorption in Mott insulators: Insights from nonequilibrium dynamical mean-field theory

We present a formalism based on nonequilibrium dynamical mean-field theory (DMFT) which allows to compute the time-resolved x-ray absorption spectrum (XAS) of photoexcited solids. By applying this formalism to the photodoped half-filled and quarter-filled two-orbital Hubbard models in the Mott insulating regime we clarify how the time-resolved XAS signal reflects the nonequilibrium population of different local states. Apart from the missing broadening associated with continuum excitations, the atomic XAS spectrum computed with the nonthermal state populations provides a good approximation to the full nonequilibrium DMFT result. This suggests a route to combine the accurate DMFT description of nonequilibrium states of solids with cluster calculations of the XAS signal.

Automated summary

This study presents a formalism based on nonequilibrium dynamical mean-field theory (DMFT) to calculate the time-resolved x-ray absorption spectrum (XAS) of photoexcited solids. By applying this formalism to specific Hubbard models, the researchers reveal how the time-resolved XAS signal relates to the population of different local states. Additionally, they find that the atomic XAS spectrum computed with nonthermal state populations can provide a good approximation to the full nonequilibrium DMFT result, indicating a potential method to combine accurate DMFT description with cluster calculations of the XAS signal.