The Electronic Structure of Europium Chalcogenides and Pnictides

TL;DR

This study uses an advanced ab-initio method to analyze the electronic structure and valency states of europium chalcogenides and pnictides, revealing their insulating or metallic nature and potential for spintronic applications.

Contribution

It applies the SIC-LSD approach to accurately describe localized f-electrons and valency variations in europium compounds from first principles.

Findings

Chalcogenides are insulators with divalent europium.

EuN is half-metallic; others are metallic.

Valence states change across the pnictide series.

Abstract

The electronic structure of some europium chalcogenides and pnictides is calculated using the {\it ab-initio} self-interaction corrected local-spin-density approximation (SIC-LSD). This approach allows both a localised description of the rare earth $f-$electrons and an itinerant description of $s$, $p$ and $d$-electrons. Localising different numbers of $f$-electrons on the rare earth atom corresponds to different nominal valencies, and the total energies can be compared, providing a first-principles description of valency. All the chalcogenides are found to be insulators in the ferromagnetic state and to have a divalent configuration. For the pnictides we find that EuN is half-metallic and the rest are normal metals. However a valence change occurs as we go down the pnictide column of the Periodic Table. EuN and EuP are trivalent, EuAs is only just trivalent and EuSb is found to be divalent. Our results suggest that these materials may find application in spintronic and spin filtering devices.