THE MAGNETIC-PROPERTIES OF THE QUATERNARY INTERMETALLIC GDNI2B2C AND GDNIBC COMPOUNDS

The magnetic features of GdNi2B2C (14/mmm, a = 3.578 Angstrom, c = 10. 361 Angstrom) and GdNiBC (P4/nmm, a = 3.631 Angstrom, c = 7.546 Angstr om) have been studied for 1.2 K < T < 300 K and in fields up to 140 kO e. In both types of compound, the spherical S-8 state of the Gd3+ ion can be unambiguously observed in the features of the paramagnetic stat e as well as the low-T field-induced ferromagnetic state. The observed Neel points for GdNi2B2C and GdNiBC are, respectively, 19.5(5) K and 14.3(5) K, and their magnetic structures at T = 0 are presumably the c ollinear Neel-type structures. The saturating field in GdNi2B2C (H gre ater than or equal to 125 kOe at 1.7 K) is approximately three times t hat of GdNiBC implying that the average interlayer interactions in the former are much stronger than in the latter. The overall magnetic fea tures of both compounds are interpreted in terms of the picture that a ssumes the Gd moments to have strong ferromagnetic intralayer coupling s and averaged antiferromagnetic interlayer interactions.