Effect of the ionic radius of A-cations on the magnetic and magnetocaloric properties of charge-ordered manganite La$_{0.5}$Ca$_{0.5-x}$Sr$_x$MnO$_3$ (0 $<x<$ 0.5)

The effect of substitution of Sr$^{2+}$ ions for Ca$^{2+}$ ions on the magnetic and magnetocaloric properties of a charge-ordered La$_{0.5}$Ca$_{0.5-x}$MnO$_3$ manganite has been studied. The direct and inverse magnetocaloric effects corresponding to the paramagnetic–ferromagnetic and ferromagnetic–antiferromagnetic transitions have been detected. It has been shown that the substitution Ca$^{2+}$ $\to$ Sr$^{2+}$ leads to the suppression of the charge-ordered phase and to an increase in the Curie temperature $T_C$. The evolution of the destruction of the charge-ordered phase is nonmonotonic, which is associated with the change in the type of antiferromagnetic ordering.