Specific heat of the ternary compoundsUPd2Si2andUNi2Si2

The specific heat of the single crystals of ${\mathrm{UPd}}_2{\mathrm{Si}}_2$ and ${\mathrm{UNi}}_2{\mathrm{Si}}_2$ has been studied using the step heating method for the temperature range between 2 and 250 K. Successive phase transitions at high temperatures were observed for both samples, which are consistent with previously reported magnetization and neutron scattering results. No evidence of any phase transition was observed at temperatures below 70 K, which has been previously reported. The Debye temperature and the electronic specific heat coefficient $\gamma$ of ${\mathrm{UPd}}_2{\mathrm{Si}}_2$ are found to be 117 K and 19 ${\mathrm{m}\mathrm{J}/\mathrm{m}\mathrm{o}\mathrm{l}\mathrm{}\mathrm{K}}^2$, respectively. In low temperatures between 2 and 4 K, an upturn in specific heat with $T^{-2}$ dependence was observed. Several possibilities for this upturn in the specific heat are discussed.