The dynamic conductivity and the plasmon profile of Aluminum in the ultra-fast-matter regime; an analysis of recent X-ray scattering data from the LCLS

TL;DR

This paper analyzes X-ray scattering data from Aluminum in the ultra-fast-matter regime using a two-temperature model and NPA calculations, explaining low conductivities and plasmon features without relying on the Mermin model.

Contribution

It introduces a two-temperature, isochoric approach combined with NPA calculations to analyze UFM Aluminum, challenging the applicability of the Mermin model and providing a new interpretation of conductivity data.

Findings

Good agreement with experimental conductivity data

Low conductivities explained by strong electron-ion scattering

Plasmon line-shape accurately modeled without Mermin response

Abstract

We use an explicitly isochoric two-temperature theory where the ion temperature is not assumed to be equal to the electron temperature, to analyze recent X-ray laser scattering data for Aluminum in the ultra-fast-matter (UFM) regime up to 6 eV, obtained at the Standford Linac Coherent Light Source (LCLS). The observed surprisingly low conductivities are explained by including strong electron-ion scattering effects using the phase shifts calculated via the density-functional neutral-pseudo-atom model (NPA). The applicability of the Mermin model to UFM is questioned. The static and dynamic conductivity, complex collision frequency and the plasmon line-shape are evaluated within a Born approximation and without the use of the Mermin response. This approach, where all needed quantities are obtained from the NPA model, provides good agreement with the reported experimental results.