Anisotropy and metamagnetism in the RNi2Ge2 (R = Y, La-Nd, Sm-Lu) series

Single crystals of a complete series of the RNi2Ge2 (R = Y, La-Nd, Sm-Lu) ternary intermetallics were grown and characterized by measurements of the anisotropic magnetization and in-plane resistivity in zero and applied magnetic field. The majority of moment-bearing members of the series order antiferromagnetically and have a series of transitions in zero applied magnetic field and there is a rough de Gennes scaling of Theta(D) and T-N for the heavy rare-earth members of the series. Signatures of the metamagnetic transitions in the magnetically ordered state and magnetic transitions in zero field are observed for a number of the members of the series. TbNi2Ge2 was studied in more details. Angular-dependent magnetization measurements support the hypothesis that the spins in the ordered states are confined to the c-axis. Complex H-T (H parallel to c) phase diagram for this material was derived from the magnetization measurements at different temperatures (M(H)) and applied fields (M(T)). It is suggested that TbNi2Ge2 is a promising candidate for the 'devil's staircase' material. In addition, YbNi2Ge2 is suggested to have strong 4f-conduction electron hybridization and is characterized as a 4f-hole analog of the previously studied CeNi2Ge2 moderate heavy fermion compound. (C) 1999 Elsevier Science B.V. All rights reserved.