Magnetic properties of R3Cu4X4 (R = Tb-Er; X = Si, Ge, Sn) compounds

dc magnetization and magnetic susceptibility measurements were performed on polycrystalline samples of R3Cu4X4 (R = Tb-Er; T = Si, Ge, Sn) intermetallics which crystallize in the orthorhombic crystal structure of the Gd3Cu4Ge4-type. All of the studied compounds are antiferromagnets showing complex behavior. For some of them additional transitions below Neel temperature are observed and few indicate metamagnetic transition at 2 K. Reciprocal magnetic susceptibilities of all the samples obey the Curie-Weiss law above the Neel temperatures with negative values of paramagnetic Curie temperatures and the effective magnetic moments of rare earth ions being close to the respective free R3+ ion values