Theory of Spin-Resolved Auger-Electron Spectroscopy from Ferromagnetic 3d-Transition Metals

TL;DR

This paper develops a theoretical framework for calculating spin-resolved Auger-electron spectra in ferromagnetic 3d transition metals, incorporating electron correlations and realistic band structures.

Contribution

It introduces a comprehensive diagrammatic approach combining perturbation theory and ladder approximation to analyze Auger spectra in ferromagnetic metals.

Findings

Calculated Auger line shapes for ferromagnetic Ni.

Analyzed the influence of core holes on spectra.

Discussed spin-resolved quasi-particle band structures.

Abstract

CVV Auger electron spectra are calculated for a multi-band Hubbard model including correlations among the valence electrons as well as correlations between core and valence electrons. The interest is focused on the ferromagnetic 3d-transition metals. The Auger line shape is calculated from a three-particle Green function. A realistic one-particle input is taken from tight-binding band-structure calculations. Within a diagrammatic approach we can distinguish between the \textit{direct} correlations among those electrons participating in the Auger process and the \textit{indirect} correlations in the rest system. The indirect correlations are treated within second-order perturbation theory for the self-energy. The direct correlations are treated using the valence-valence ladder approximation and the first-order perturbation theory with respect to valence-valence and core-valence interactions. The theory is evaluated numerically for ferromagnetic Ni. We discuss the spin-resolved quasi-particle band structure and the Auger spectra and investigate the influence of the core hole.