Antiferromagnetic ordering in the ternary uranium germanide UNi1–xGe2: Neutron diffraction and physical properties studies

The compound UNi0.45Ge2 was studied by means of X-ray diffraction (XRD), magnetization, neutron diffraction, specific heat and electrical resistivity measurements performed in wide ranges of temperature and magnetic field. The single-crystal XRD experiment indicated that the material crystallizes in the orthorhombic CeNiSi2-type structure with the lattice parameters a = 4.1062(2) Å, b = 15.9272(8) Å and c = 4.0461(2) Å. The physical properties measurements showed that it orders antiferromagnetically at TN = 47 K. The magnetic ordering was confirmed by the neutron diffraction experiment, which revealed that the ordered magnetic moments are aligned along the crystallographic b-axis in a sequence −++−. In strong magnetic fields, a distinct field-induced first-order metamagnetic phase transition occurs, characterized by a large magnetic hysteresis. Temperature and field variations of the electrical resistivity are strongly affected by the atom disorder in the crystallographic unit cell of the investigated compound. [Display omitted] •UNi0.45Ge2 crystallizes in a Ni-deficient CeNiSi2 orthorhombic structure-type.•Antiferromagnetic ordering below TN = 47 K with moments oriented along the b-axis.•Electrical (magneto)resistivity is influenced by crystallographic disorder.•Metamagnetic transition above 10 T with huge hysteresis (4 T at 2 K): 1st order?