Crystal Structure and Magnetic Properties of Uranium Hydride UH2 Stabilized as a Thin Film.

A new type of uranium binary hydride, UH2, with the CaF2 crystal structure, was synthesized in a thin-film form using reactive sputter deposition at low temperatures. The material has a grain size of 50-100 nm. The lattice parameter a = (535.98 ± 0.14 pm) is close to that in known Np (534.3 pm) and Pu (535.9 pm) iso-types. UH2 is a metallic ferromagnet with the Curie temperature TC ≈ 120 K. A very wide hysteresis loop indicates strong magnetocrystalline anisotropy. X-ray photoelectron spectroscopy reveals similarities with electronic structure of UH3, which is also ferromagnet with higher TC = 165 K.