Magnetic anomalies of thermal expansion in (rare-earth) Ni2 intermetallic compounds

The thermal expansion of eight RENi₂ intermetallic compounds (RE = La, Nd, Sm, Tb, Dy, Ho, Er, Tm) and YNi₂ have been measured between 3.8 and approx. 300 K. The anomalies found at the paramagnetic-magnetically ordered phase transition have allowed an accurate determination of the Curie temperatures. From the low temperature comparison of the thermal expansion of the light RE compounds with that of LaNi₂, and of the heavy RE compounds with that of YNi₂, the Debye temperatures have been obtained. In the case of the compounds DyNi₂, TbNi₂ and HoNi₂ the contributions from crystal field and exchange interactions to the spontaneous volume strain at the magnetically ordered phase have been calculated, the agreement between experiment and calculation being good.