High rare earth sublattice ordering temperatures in new CeFeSi-type RTiGe (R≡La-Nd, Sm) compounds

Investigations made by powder X-ray diffraction and susceptibility measurements on ternary germanides RTiGe (R≡La-Nd, Sm, Lu) are reported. All these new compounds crystallize in the well-known tetragonal structure of the CeFeSi-type (space group P4/nmm). LaTiGe and LuTiGe are Pauli paramagnets. CeTiGe is characterized by Curie-Weiss paramagnetism down to 5 K, whereas PrTiGe, NdTiGe and SmTiGe behave antiferromagnetically below 70, 150 and 265 K, respectively. Low temperature (T<77 K) investigations of the corresponding heavy rare earth compounds show that ErTiGe and TmTiGe are antiferromagnetic below 41 and 15 K, respectively. Metamagnetic-like behaviour occurs in ErTiGe, TmTiGe (Hc≅2 kOe) and HoTiGe (Hc≅5 kOe). These results are discussed and compared with those of isotypic ternary RTX (T≡Mn, Fe, Co, Ru; X≡Si, Ge) compounds. (orig.)