Specific Heat of Yttrium Iron Garnet from 1.5° to 4.2°K

The specific heats of two samples of yttrium iron garnet have been measured between 1.5 and 4.2°K. The data have been analyzed into lattice- and spin-wave contributions characterized, respectively, by the Debye temperatures ${\Theta }_1=538\mathrm{}°$K, ${\Theta }_2=567\mathrm{}°$K, and by $D_1=0.81\mathrm{}\times {10}^{-28\mathrm{}}$ erg-${\mathrm{cm}}^2$, $D_2=0.85\mathrm{}\times {10}^{-28\mathrm{}}$ erg-${\mathrm{cm}}^2$, where $D$ is defined by the dispersion relation for spin waves, $\hslash \omega =D{k}^2$.