Quantifying the U \(5f\) covalence and degree of localization in U intermetallics

• Published in: arXiv.org 2024-07
• Main Authors: Marino, Andrea, Christovam, Denise S, Takegami, Daisuke, Falke, Johannes, Carvalho, Miguel M F, Takaki Okauchi, Chun-Fu, Chang, Altendorf, Simone G, Amorese, Andrea, Sundermann, Martin, Gloskovskii, Andrei, Gretarsson, Hlynur, Keimer, Bernhard, Andreev, Alexandr V, Havela, Ladislav, Leithe-Jasper, Andreas, Severing, Andrea, Kunes, Jan, Liu, Hao Tjeng, Hariki, Atsushi
• Format: Article
• Language: English
• Subjects: Covalence; Density functional theory; Intermetallic compounds; Localization; Mean field theory; Photoelectrons; Photoionization; Soft x rays; Spectrum analysis; Valence band; X ray photoelectron spectroscopy
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2404.06266

A procedure for quantifying the U \(5f\) electrons' covalence and degree of localization in U intermetallic compounds is presented. To this end, bulk sensitive hard and soft x-ray photoelectron spectroscopy were utilized in combination with density-functional theory (DFT) plus dynamical mean-field theory (DMFT) calculations. The energy dependence of the photoionization cross-sections allows the disentanglement of the U\,\(5f\) contribution to the valence band from the various other atomic subshells so that the computational parameters in the DFT\,+\,DMFT can be reliably determined. Applying this method to UGa\(_2\) and UB\(_2\) as model compounds from opposite ends of the (de)localization range, we have achieved excellent simulations of the valence band and core-level spectra. The width in the distribution of atomic U\,\(5f\) configurations contributing to the ground state, as obtained from the calculations, quantifies the correlated nature and degree of localization of the U\,5\(f\). The findings permit answering the longstanding question why different spectroscopic techniques give seemingly different numbers for the U 5\(f\) valence in intermetallic U compounds.