Multiple magnetic transitions in R3CoGe2 compounds (R=Ce, Pr and Nd)

Abstract Magnetic properties of R 3 CoGe 2 (R=Ce, Pr and Nd) have been determined, using magnetisation, low temperature heat capacity and electrical resistivity. The compounds crystallise in the La 3 NiGe 2 -type orthorhombic structure; three symmetry in-equivalent rare earth sites are present in the unit cell. La 3 NiGe 2 was also prepared as non-magnetic reference for the comparison of heat capacity data, since most likely a homologous compound with stoichiometry ‘La 3 CoGe 2 ’ does not form. Two magnetic transitions occur in Ce 3 CoGe 2 (3.4 and 6 K) and Nd 3 CoGe 2 (8.8 and 35 K) while Pr 3 CoGe 2 exhibits a single ferromagnetic transition at 28 K. The transition at higher temperatures in both Ce 3 CoGe 2 and Nd 3 CoGe 2 is ferromagnetic while the transition at lower temperatures is antiferromagnetic. The data indicate that the two transitions involve Ce and Nd ions belonging to different sub-lattices. The presence of the Kondo interaction in Ce 3 CoGe 2 is also inferred from the data.