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arXiv · 2601.03902

Electronic Structure of UGe$_{2\pm x}$ Thin Films from Photoelectron Spectroscopy

Sonu George Alex·Oleksandr Romanyuk·Ivan Zorilo·Alexander Andreev·Frank Huber·Thomas Gouder·Petr Malinsky·Maliha Siddiqui·Alexander B. Shick·Evgenia A. Tereshina-Chitrova
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Abstract

Uranium digermanide UGe$_2$, the first ferromagnetic superconductor, represents a key composition in the U-Ge system dominated by U-5$f$ states. To examine the impact of controlled stoichiometric deviations on the electronic structure, UGe$_{2\pm x}$ thin films ($0 \le x \le 1$) were prepared by triode sputtering and studied on pristine surfaces by X-ray (XPS) and Ultraviolet (UPS) photoelectron spectroscopy. XPS and UPS reveal a robust metallic valence band with a dominant U-5$f$ contribution at the Fermi level and a broad incoherent feature at higher binding energies, without qualitative changes in spectral line shape across the composition range. The experimental spectrum of UGe$_2$ thin films is well reproduced by DFT+U(ED) valence-band calculations combining density functional theory with exact diagonalization of the multiconfigurational U-5$f$ shell. These results demonstrate that the overall U-Ge electronic framework of UGe$_2$ thin films remains resilient to moderate stoichiometric deviations, providing a reliable electronic baseline for future studies of interface- and heterostructure-driven phenomena in uranium-based systems.

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Sonu George Alex, Oleksandr Romanyuk, Ivan Zorilo, Alexander Andreev, Frank Huber, Thomas Gouder, Petr Malinsky, Maliha Siddiqui, Alexander B. Shick, Evgenia A. Tereshina-Chitrova. 2026-01-07. Electronic Structure of UGe$_{2\pm x}$ Thin Films from Photoelectron Spectroscopy. https://doi.org/10.1016/j.elspec.2026.147611

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