Neutron diffraction studies on structural and magnetic properties of RE₂NiGe₃ (RE=La, Ce)

Abstract

We report the crystallographic properties of RE₂NiGe₃ (RE=La, Ce) synthesized by arc melting. Rietveld refinement on the powder neutron diffraction (ND) data suggest both compounds are isostructural and crystallize in the non-centrosymmetric Er₂RhSi₃ type structure having hexagonal space group P6‾2c. In the crystal structure of RE₂NiGe₃, two dimensional arrangements of nickel and germanium atoms lead to the formation of hexagonal layers with rare earth atoms sandwiched between them. Magnetic susceptibility measurements performed in low fields exhibit antiferromagnetic ordering in cerium compound around (T_o=) 3.2 K. Neutron diffraction measurements at 2.8 K (i.e., at T<T_o) neither show any change in the intensities of the diffraction lines nor indicate the appearance of any new diffraction lines in the Q-range of 0.47-7.34Å^-1, thus ruling out any long-range magnetic order.