Spin and Orbital Magnetism in UH2 Thin Films Studied by X-ray Magnetic Circular Dichroism
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2025
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| author | Tereshina-Chitrova, Evgenia A. Paukov, Mykhaylo Koloskova, Oleksandra Hen, Amir Wilhelm, Fabrice Horak, Lukas Celis, Mayerling Martinez Cieslar, Miroslav Havela, Ladislav Rogalev, Andrei Gouder, Thomas |
| author_facet | Tereshina-Chitrova, Evgenia A. Paukov, Mykhaylo Koloskova, Oleksandra Hen, Amir Wilhelm, Fabrice Horak, Lukas Celis, Mayerling Martinez Cieslar, Miroslav Havela, Ladislav Rogalev, Andrei Gouder, Thomas |
| contents | Uranium dihydride UH2 is a metastable phase unknown in bulk form but accessible through thin-film synthesis. We prepared UH2 films by reactive dc sputtering on CaF2(001) or Si(001) substrates, the latter equipped with a Mo buffer layer to suppress a U-Si interdiffusion. On CaF2, UH2 adopts the fluorite-type structure with a near-[1 1 1] out-of-plane texture, four rotational domains, and a lattice parameter a = 539 +- 3 pm without measurable strain, whereas the Mo-buffered film is polycrystalline. X-ray photoelectron spectroscopy confirmed complete hydrogenation and minimal oxidation. Magnetization and XMCD measurements show ferromagnetic ordering with Curie temperatures of 120-130 K and a uranium 5f moment of 0.9 μB/U, dominated by the orbital contribution (μL ~ 1.4 μB, μS ~ -0.5 μB), in a good agreement with GGA+U computations, which otherwise overestimate absolute values of the spin and orbital components. The slightly reduced moment in thinner CaF2-supported films is attributed to surface U(IV) species. These results demonstrate that thin-film synthesis enables stabilization of UH2 and direct probing of 5f magnetism, opening pathways toward higher uranium hydrides and interface-engineered actinide systems. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2512_07183 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Spin and Orbital Magnetism in UH2 Thin Films Studied by X-ray Magnetic Circular Dichroism Tereshina-Chitrova, Evgenia A. Paukov, Mykhaylo Koloskova, Oleksandra Hen, Amir Wilhelm, Fabrice Horak, Lukas Celis, Mayerling Martinez Cieslar, Miroslav Havela, Ladislav Rogalev, Andrei Gouder, Thomas Materials Science Uranium dihydride UH2 is a metastable phase unknown in bulk form but accessible through thin-film synthesis. We prepared UH2 films by reactive dc sputtering on CaF2(001) or Si(001) substrates, the latter equipped with a Mo buffer layer to suppress a U-Si interdiffusion. On CaF2, UH2 adopts the fluorite-type structure with a near-[1 1 1] out-of-plane texture, four rotational domains, and a lattice parameter a = 539 +- 3 pm without measurable strain, whereas the Mo-buffered film is polycrystalline. X-ray photoelectron spectroscopy confirmed complete hydrogenation and minimal oxidation. Magnetization and XMCD measurements show ferromagnetic ordering with Curie temperatures of 120-130 K and a uranium 5f moment of 0.9 μB/U, dominated by the orbital contribution (μL ~ 1.4 μB, μS ~ -0.5 μB), in a good agreement with GGA+U computations, which otherwise overestimate absolute values of the spin and orbital components. The slightly reduced moment in thinner CaF2-supported films is attributed to surface U(IV) species. These results demonstrate that thin-film synthesis enables stabilization of UH2 and direct probing of 5f magnetism, opening pathways toward higher uranium hydrides and interface-engineered actinide systems. |
| title | Spin and Orbital Magnetism in UH2 Thin Films Studied by X-ray Magnetic Circular Dichroism |
| topic | Materials Science |
| url | https://arxiv.org/abs/2512.07183 |