Correlation between magnetic and electrical properties of the superparamagnetic La0.6Ca0.4MnO3 compound

In this research work, we investigated the correlation between the electrical and magnetic properties of the superparamagnetic compound La_0.6Ca_0.4MnO₃ $\left(S0C1\right)$ prepared by the citric-gel method. The confrontation of the experimental data with the theoretical models revealed that the conduction at low temperatures, in the ferromagnetic metallic $\left(FMM\right)$ phase, can be mainly described by electron–electron $(e-e)$ and electron-magnon $(e-m)$ interactions. The contribution of the $(e-m)$ interaction, became weak for strong magnetic fields. At high temperatures, in the paramagnetic semiconductor $\left(PMSC\right)$ phase, the thermally activated hopping $\left(TAH\right)$ model proved to be the most appropriate to fit the experimental data. To describe the resistivity behavior in a wide temperature range including the phase transition region between the $\left(FMM\right)$ and $\left(PMSC\right)$ phases, we adopted the percolation model, based on the phase segregation mechanism.