MAGNETIC-PROPERTIES OF RNISI(2) AND RNIGE(2) COMPOUNDS

The series of ternary silicides and germanides RNiX(2) (R-rare earth, X = Si or Ge) with an orthorhombic CeNiSi2-type structure have been investigated by X-ray diffraction and magnetometric measurements. CeNiSi2 is a mixed valence system and SmNiGe2 has a nonmagnetic state at low temperatures. CeNiGe2 and SmNiSi2 are antiferromagnets. The compounds with R = Pr and Nd are ferromagnets while those containing R = Gd, Tb, Dy, Ho and Er are antiferromagnets with a Neel temperatures below 42 K. For both Si and Ge groups of compounds the Neel temperatures do not follow de Gennes scaling. This behaviour of T-N can be understood on the basis of crystalline-electric field effects.