Measurement of Specific Heat of Pr$_{\mathrm{1-x}}$Nd$_{\mathrm{x}}$Os$_{4}$Sb$_{12}$ from 11K-300K

The filled skutterudite compound PrOs$_{4}$Sb$_{12}$ exhibits heavy fermion behavior and unconventional superconductivity at low temperatures (T$_{\mathrm{c}}=$1.85K). The exact causes of these behaviors are unknown. The compound NdOs$_{4}$Sb$_{12}$ exhibits ferromagnetism at a Curie temperature near 1 K. Originally, Nd doped compounds of the form Pr$_{\mathrm{1-x}}$Nd$_{\mathrm{x}}$Os$_{4}$Sb$_{12}$ were developed to investigate the effect of ferromagnetism on the unconventional superconductivity and heavy fermion behavior of PrOs$_{4}$Sb$_{12}$. The specific heat of Pr$_{\mathrm{1-x}}$Nd$_{\mathrm{x}}$Os$_{4}$Sb$_{12}$ (where x$=$0.25, 0.5, 0.75, 0.8, and 1) is measured at 11K-300K to investigate the compounds' normal state properties. The specific heat is measured using relaxation calorimetry of finite heat pulse in a cryocooler system. Values of the electronic specific heat coefficient, $\gamma $, for these compounds are estimated to be 10-60 mJ/K$^{2}$-mol. This contrasts with previous low temperature measurements (\textless 10K) of NdOs$_{4}$Sb$_{12}$ with $\gamma $ approximately 520 mJ/K$^{2}$-mol.