Study of the Magnetocaloric Effect by Means of Theoretical Models in La 0.6 Ca 0.2 Na 0.2 MnO 3 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 La 0.6 Ca 0.2 Na 0.2 MnO 3 manganite. Results showed that sample exhibits second-order ferromagnetic (FM)–paramagnetic (PM) magnetic phase transition and relatively higher values of magnetic entropy change ( − ∆S M ). In application point of view, this material can be used in magnetic refrigeration technology. The theoretical values of − ∆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 s pont ( T ), estimated from ( − ∆S M vs. M 2 ) and ( H / M vs. M 2 ) data was found. Also, the values of the critical exponent ( β ) found from both methods are close and check that the mean-field model is adequate to study the MCE in La 0.6 Ca 0.2 Na 0.2 MnO 3 sample.