Phase transitions in NdNiPb and $Nd5NiPb3$

We report magnetic and thermodynamic measurements for NdNiPb and $Nd5NiPb3$⁠. High-temperature Curie-Weiss fits yield effective moments per Nd of $3.59μB$ for NdNiPb and $3.70μB$ for $Nd5NiPb3$⁠. These are close to the $Nd3+$ ionic moment, $3.62μB$⁠, showing that Ni is nonmagnetic in both cases. For NdNiPb a peak seen in both the magnetization and specific heat at $3.5K$ indicates an antiferromagnetic transition at that temperature. Specific heat measurements show this transition to be formed from crystal-field-split Nd magnetic levels, and a fit yields values for crystal field splitting. $Nd5NiPb3$ exhibits two magnetic transitions, an antiferromagnetic transition at $42K$⁠, and an apparently weak-ferromagnetic canting transition at $8K$⁠. These are confirmed by specific heat measurements. $M-H$ curves show metamagnetism at temperatures between the two magnetic transitions.