Ferromagnetic suppression of the charge-ordering temperature in La_1-xCa_xMnO₃

We present the results of our detailed dc magnetization and susceptibility studies on La_1-xCa_xMnO₃ for 0.53≤x≤0.70 in the charge-ordered (CO) and antiferromagnetic phase. Field dependence of the magnetization for x<0.65 shows a nonlinear behavior below 1 T, which indicates the presence of a ferromagnetic phase. This nonlinear behavior gets stronger with x becoming closer to 0.5, where a phase boundary exists between the ferromagnetic and the CO antiferromagnetic phases. From the temperature dependence of the magnetization, we also observe that this ferromagnetic component starts to develop just below the charge-ordering temperature. This concentration and temperature dependence of the ferromagnetic component suggests that its coexistence and competition with the CO phase cause a drop in the CO transition temperatures for 0.50<x<0.625.