Study of the Magnetocaloric Effect by Means of Theoretical Models in La0.6Ca0.2Na0.2MnO3 Manganite Compound

In this work, an overview of the Weiss molecular mean-field theory, the Bean-Rodbell model and the Landau theory is presented, providing the theoretical background for simulating the magnetocaloric properties for La0.6Ca0.2Na0.2MnO3 manganite. Results showed that sample exhibits second-order ferromagnetic (FM)-paramagnetic (PM) magnetic phase transition and relatively higher values of magnetic entropy change (- increment S-M). In application point of view, this material can be used in magnetic refrigeration technology. The theoretical values of - increment S-M determined using each theory agree well with the experimental ones estimated from Maxwell relations. In other part, a good agreement in the spontaneous magnetization values, M-spont(T), estimated from (- increment S-M vs. M-2) and (H/M vs. M-2) data was found. Also, the values of the critical exponent (beta) found from both methods are close and check that the mean-field model is adequate to study the MCE in La0.6Ca0.2Na0.2MnO3 sample.