Electronic structure of YbFe4Al8 antiferromagnet: A combined X-ray photoelectron spectroscopy and first-principles study

• Published in: Journal of alloys and compounds 2022-07, Vol.910, p.164478, Article 164478
• Main Authors: Marciniak, Wojciech, Chełkowska, Grażyna, Bajorek, Anna, Kowalczyk, Andrzej, Szajek, Andrzej, Werwiński, Mirosław
• Format: Article
• Language: English
• Subjects: Antiferromagnetism; Charge transfer; Chemical composition; Chemical compounds; Configurations; Density functional theory; Electronic structure; First principles; Magnetic moments; Magnetism; Photoelectrons; Room temperature; Spectrum analysis; Transition metal rare-earth alloys; Valence; Valence band; X ray photoelectron spectroscopy; YbFe4Al8
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2022.164478

Depending on their chemical composition, Yb compounds often exhibit different valence states. Here we investigate the valence state of YbFe4Al8 using X-ray photoelectron spectroscopy (XPS) and first-principles calculations. The XPS valence band of YbFe4Al8 consists of two contributions coming from divalent (Yb2+) and trivalent (Yb3+) configurations. The determined value of the valence at room temperature is 2.81. Divalent and trivalent contributions are also observed for core-level Yb 4d XPS spectra. We study several collinear antiferromagnetic models of YbFe4Al8 from the first-principles and for comparison we also consider LuFe4Al8 with a fully filled 4f shell. We predict that only Fe sublattices of YbFe4Al8 carry significant magnetic moments and that the most stable magnetic configuration is AFM-C with antiparallel columns of magnetic moments. We also present a Mulliken electronic population analysis describing charge transfer both within and between atoms. In addition, we also study the effect of intra-atomic Coulomb U repulsion term applied for 4f orbitals on Yb valence and Fe magnetic moments. •The valence of YbFe4Al8 from the relative intensity of Yb2+ and Yb3+ XPS peaks is 2.81 at room temperature.•The AFM-C configuration has the lowest energy among the considered colinear antiferromagnetic configurations.•We performed full structure optimization and present the resultant complete structural model of the YbFe4Al8 AFM-C structure.•The occupation of the 4f orbital from Mulliken analysis is ~13.5 (at 0 K), higher than the valence deduced from XPS spectra.