Phase transition in electronic manganite Ca$_{0.85}$Sm$_{0.15}$MnO$_3$

The resistivity, the magnetic susceptibility, the magnetization, and the specific heat of electronic manganite Ca$_{0.85}$Sm$_{0.15}$MnO$_3$ were studied. The data obtained suggest that this compound undergoes phase transition into the insulator antiferromagnetic state at $T_c\sim115\,$ K and displays negative magnetoresistance at $T<T_c$. A minor ferromagnetic component of $0.025\mu_B$ in the magnetization of Ca$_{0.85}$Sm$_{0.15}$MnO$_3$ may be caused by the deviation of this composition from the exact stoichiometry Mn$^{3+}:{}$Mn$^{4+}=1:8$. The Debye temperature $\Theta_D=575\,$ K and the entropy of phase transition $\Delta S=5.1\,$ J/(mol K) were derived from the temperature dependence of specific heat.