Magnetic properties of some equiatomic ternary rare-earth compounds.

Interesting and diverse magnetic behavior has been reported in the literature on the rare-earth-based equiatomic ternary compounds. For example, CeGeGa (Ref. l) and possible CePdSb (Ref. 2) are dense Kondo ferromagnets, while hybridization-induced pseudogap formation at the Fermi level at low temperatures occurs in the nonmagnetic CeRhSb (Ref. 3) and CeNiSn. ' A massive heavy-electron state with a Sommerfeld coeScient of about 8 J/molK has been reported in the low-carrierdensity compound YbPtBi which undergoes an antiferromagnetic phase transition near 0.4 K. In YbNiSb, which is isostructural to YbPtBi and orders at 0.8 K, an unusually large magnetic-Geld dependence of the heat capacity and a large decrease in the electrical resistivity below 150 K are observed. It is, therefore, of interest to investigate the magnetic behavior of other rare-earthbased equiatomic ternary compounds known in the literature. With that in mind we have studied in the present work the compounds CeZnIn, YbZnIn, and CePbCu. GdPbCu and the nonmagnetic LaPbCu were also studied for the sake of comparison with the properties of CePbCu. The synthesis of Rznln and RPbCu (R =La —Yb) was reported by Mazzone et al. They reported that the crystal structure of these compounds were related to the hexagonal hP6, CaIn2 type (space group P63/mmc ). The two atoms of the rare earth occupy the b position while the other two atoms occupy the f position at random. An ordered arrangement of the non-rare-earth atoms at the f site, however, was not ruled out by them. The lattice parameters of RZnIn and RPbCu followed the usual behavior due to the lanthanide contraction of trivalent rare-earth ions, but for the compounds containing Yb the lattice volume was larger, indicating a fluctuating or divalent state of the Yb ions.