Effects of hydrogenation on magnetism of UNiGe

U-based intermetallic compound UNiGe absorbs hydrogen up to the stoichiometry UNiGeH1.2. In analogy to other compounds with the TiNiSi-type of structure, the structure is modified into hexagonal. The zig-zag U-chains are stretched, the U–U spacing is largely enhanced and the ordering temperature increases up to 100 K. The ordered state has a spontaneous moment, but it is unlikely to be a simple ferromagnet.

► UNiGe exhibits a variety of magnetic properties.
► Hydrogenation modifies the crystal, electronic structure, and the magnetic properties.
► Upon hydrogenation, the crystal symmetry of UNiGe increases from orthorhombic to hexagonal.
► Magnetic ordering temperature of UNiGe (TN=44 K) is double in the hydride, possible second phase transition.