Correlated Electrons Step-by-Step: Itinerant-to-Localized Transition of Fe Impurities in Free-Electron Metal Hosts

TL;DR

This study combines experimental spectroscopy and ab-initio calculations to explore how Fe impurities transition from itinerant to localized states in free-electron metals, revealing complex hybridization behaviors.

Contribution

It provides a detailed analysis of the evolution of Fe impurity electronic states using combined experimental and theoretical methods, highlighting the transition from delocalized to localized electrons.

Findings

Gradual dissolution of multiplet structure into quasiparticle peak

Hybridization strength depends on host electron density

Effective multi-orbital impurity model accurately describes the transition

Abstract

High-resolution photoemission spectroscopy and realistic ab-initio calculations have been employed to analyze the onset and progression of d-sp hybridization in Fe impurities deposited on alkali metal films. The interplay between delocalization, mediated by the free-electron environment, and Coulomb interaction among d-electrons gives rise to complex electronic configurations. The multiplet structure of a single Fe atom evolves and gradually dissolves into a quasiparticle peak near the Fermi level with increasing the host electron density. The effective multi-orbital impurity problem within the exact diagonalization scheme describes the whole range of hybridizations.