Magnetism of R2Ti3Ge4 (R=Sc, Gd, Tb, Dy, Ho, and Er) compounds

Results of magnetization measurements down to 1.8 K on polycrystalline R2Ti3Ge4 (R=Sc, Gd, Tb, Dy, Ho, and Er) compounds of orthorhombic Sm5Ge4-type (space group Pnma) are presented and discussed. Gd2Ti3Ge4 is found to be a ferromagnet below 32 K while other R2Ti3Ge4 compounds, with magnetic rare earths (R=Tb, Dy, Ho, and Er), undergo a low temperature antiferromagnetic transition. The effective magnetic moment (mu(eff)) values obtained from the Curie-Weiss paramagnetic susceptibility correspond to that of R3+ ions. Saturation of magnetization is not observed upto applied fields of 5.5 T at 1.8 K for all R2Ti3Ge4 compounds except Gd2Ti3Ge4, indicating the possible presence of crystal field effects. Electrical resistivity of these compounds is dominated by electron-phonon scattering above 20 K and signature of phonon and magnon drag effects are seen in the low temperature thermopower data. (C) 2004 American Institute of Physics.