Uranium digermanide UGe2, the first ferromagnetic superconductor, represents a key composition in the U-Ge system dominated by U-5f states. To examine the impact of controlled stoichiometric deviations on the electronic structure, UGe2±x thin films (0≤x≤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-5f 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 UGe2 thin films is well reproduced by DFT+U(ED) valence-band calculations combining density functional theory with exact diagonalization of the multiconfigurational U-5f shell. These results demonstrate that the overall U-Ge electronic framework of UGe2 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.
@article{arxiv.2601.03902,
title = {Electronic Structure of UGe$_{2\pm x}$ Thin Films from Photoelectron Spectroscopy},
author = {Sonu George Alex and Oleksandr Romanyuk and Ivan Zorilo and Alexander Andreev and Frank Huber and Thomas Gouder and Petr Malinsky and Maliha Siddiqui and Alexander B. Shick and Evgenia A. Tereshina-Chitrova},
journal= {arXiv preprint arXiv:2601.03902},
year = {2026}
}