Many-body effects in the mesoscopic x-ray edge problem

TL;DR

This paper explores how many-body effects influence the x-ray edge problem in mesoscopic systems, revealing deviations from metallic behavior and size-dependent differences in photoabsorption characteristics.

Contribution

It demonstrates the impact of mesoscopic size and chaotic electron dynamics on many-body phenomena in the x-ray edge problem, highlighting deviations from bulk metallic responses.

Findings

Mesoscopic systems show a peaked K-edge, unlike the rounded edge in metals.

Photoabsorption cross section behavior depends on system size and electron dynamics.

Deviations from traditional metallic responses are significant at nanoscale dimensions.

Abstract

Many-body phenomena, a key interest in the investigation of bulk solid state systems, are studied here in the context of the x-ray edge problem for mesoscopic systems. We investigate the many-body effects associated with the sudden perturbation following the x-ray excitation of a core electron into the conduction band. For small systems with dimensions at the nanoscale we find considerable deviations from the well-understood metallic case where Anderson orthogonality catastrophe and the Mahan-Nozieres-DeDominicis response cause characteristic deviations of the photoabsorption cross section from the naive expectation. Whereas the K-edge is typically rounded in metallic systems, we find a slightly peaked K-edge in generic mesoscopic systems with chaotic-coherent electron dynamics. Thus the behavior of the photoabsorption cross section at threshold depends on the system size and is different for the metallic and the mesoscopic case.