Modeling of magnetic and magnetocaloric properties by the molecular mean field theory in La0.8Ca0.2MnO3 oxides with first and second magnetic phase transition.

Highlights • La 0.8 Ca 0.2 MnO 3 compounds show a magnetic transition from ferromagnetic to paramagnetic state. • Magnetic order phase transition are confirmed using the Bean-Rodbell model. • Magnetic measurement are simulated in bases of the mean-field theory. • We found a good medialization of the magnetic entropy change. Abstract Magnetic and magnetocaloric properties of La 0.8 Ca 0.2 MnO 3 manganese oxides has been analyzed based on the mean-field theory. The Bean-Rodbell equation of state shows a second and first order magnetic phase transition for the sample annealed at 1200 °C (S 1) and 800 °C (S 2) with a η factor of η = 0.6 and η = 1.4 respectively. Using the experimental data of magnetization M (H,T), the molecular mean-field parameter are found to be λ 1 = 0.6564 T g eum−1 and λ 1 = 0.8876 T g eum−1 for S 1 et S 2 respectively. Brillouin function allows us to determine the total angular moment J, the saturation magnetization M S and the Lande factor g for all samples. Knowing all these parameters, and by applying the mean-field theory, we simulated the magnetization as a function of the magnetic field and the temperature, as well as the variation of the magnetic entropy change ΔS M (T). We can see that the simulated results are in good agreement with experimental data. [ABSTRACT FROM AUTHOR]