Electronic Structure of FeAl Alloy Studied by Resonant Photoemission Spectroscopy and Ab Initio Calculations

TL;DR

This study combines resonant photoemission spectroscopy and ab initio calculations to analyze Fe 3d states in FeAl alloy, revealing their dual itinerant and localized nature influenced by order and disorder in the material.

Contribution

It provides a detailed understanding of the electronic structure of FeAl alloy, highlighting the coexistence of ordered and disordered phases affecting Fe 3d states.

Findings

Fe 3d states have both itinerant and localized characters.

Ordered B2 structure causes itinerant Fe 3d states.

Disorder in the sample leads to localized Fe 3d states.

Abstract

Resonant photoemission spectroscopy has been used to investigate the character of Fe 3d states in FeAl alloy. Fe 3d states have two different character, first is of itinerant nature located very close to the Fermi level, and second, is of less itinerant (relatively localized character), located beyond 2 eV below the Fermi level. These distinct states are clearly distinguishable in the resonant photoemission data. Comparison between the results obtained from experiments and first principle based electronic structure calculation show that the origin of the itinerant character of the Fe 3d states is due to the ordered B2 structure, whereas the relatively less itinerant (localized) Fe 3d states are from the disorders present in the sample. The exchange splitting of the Fe 3s core level peak confirms the presence of local moment in this system. It is found that the itinerant electrons arise due to the hybridization between Fe 3d and Al 3s-3p states. Presence of hybridization is observed as a shift in the Al 2p core-level spectra as well as in the X-ray near edge absorption spectra towards lower binding energy. Our photoemission results are thus explained by the co-existence of ordered and disordered phases in the system.