Low temperature crystal structure and magnetic properties of RAl2.

Low temperature crystal structure and magnetic properties of RAl₂ (R=Pr and Nd) have been studied using temperature dependent powder x-ray diffraction, magnetization, and heat capacity measurements. Unlike PrAl₂, NdAl₂ retains cubic MgCu₂-type structure from room temperature down to 5K, which is also confirmed from first principles electronic structure calculations. The magnetization measurements show both PrAl₂ and NdAl₂ order ferromagnetically at T_C=32K and 77 K, respectively. However, the magnetization measurements show the former is a hard ferromagnet compared to the latter which is a soft ferromagnetic material. The magnetic entropy change obtained from heat capacity measurements at ΔH=30 kOe for PrAl₂ and NdAl₂ are 3.15 Jmol^-1 K^-1 and 1.18 Jmol^-1 K^-1, respectively. [ABSTRACT FROM AUTHOR]