Effects of mixed rare earth occupancy on the low temperature properties of (R, R^′, R^″ ...) Ni₂ Ge₂ single crystals

Temperature and applied magnetic field dependent magnetization measurements on 34 single crystalline samples of (R, R^′, R^″ ...) Ni₂ Ge₂ compounds (R, R^′, R^″, etc. being primarily Gd-Lu, Y), were made. These measurements reveal that, despite extremes in local moment anisotropy, the average de Gennes parameter is a remarkably good predictor of the paramagnetic to antiferromagnetic ordering temperature. In addition, the pronounced metamagnetic phase transitions seen in the low temperature phase of TbNi₂ Ge₂ are found to be remarkably robust to high substitution levels of Gd and 25% substitutions of other heavy rare earths.