Magnetic transitions in RPd2Ge (R=Tb, Dy, Ho, Er)

Results of AC susceptibility and DC magnetization measurements for polycrystalline samples of RPd2Ge (R=Tb, Dy, Ho and Er) are presented. All the compounds crystallize in the orthorhombic Fe3C-type structure (space group is Pnma) and are antiferromagnets with the Neel temperature of 21 K for Tb, 16 K for Dy, 6.5 K for Ho and 3 K for Er, respectively. Moreover, below TN, at temperatures Tt roughly equal to TN/2, the data give the evidence for additional phase transitions to another antiferromagnetic state. The characteristic feature of the low-temperature phase is large anisotropy, while for high-temperature phase the anisotropy is smaller and a possibility of the weak uncompensation of the magnetic moments appears. Isothermal magnetization curves for TbPd2Ge and DyPd2Ge show a metamagnetic behaviour with the threshold field and the field-induced hysteresis decreasing with temperature. Irreversibility in the ZFC-FC magnetization temperature runs and the weak frequency dependence of the AC susceptibility are not connected with the spin-glass-like character of the investigated samples. Conclusions of the study are compared with the results of the magnetic neutron diffraction recently published