Low-Temperature Heat Capacity of LaPt2 and CePt2 and the Magnetic Susceptibility of CePt2

Abstract

The heat capacity of La${\mathrm{Pt}}_2$ and Ce${\mathrm{Pt}}_2$ has been measured from 1.3 to 9°K and the magnetic susceptibility of Ce${\mathrm{Pt}}_2$ from 1.3 to 80°K. La${\mathrm{Pt}}_2$ behaves as a normal metal with $\gamma =1.\mathrm{}17$ mJ/g atom°${\mathrm{K}}^2$ and ${\Theta }_D=236\mathrm{} {}_{}{}^{\circ }{}_{}{}^{}K$. Ce${\mathrm{Pt}}_2$ orders antiferromagnetically at (1.6 ± 0.1)°K. The magnetic-susceptibility behavior and the entropy of ordering can be explained on the basis of a crystal-field splitting of the $J=\frac{5}{2}$ multiplet into a ground-state doublet and an excited quartet lying 216°K above the doublet.