LAUSR

Magnetic entropy change (−ΔSM) of Nd0.67 Ba0.33Mn0.98Fe0.02O3 perovskite have been analyzed by means of theoretical models. An excellent agreement has been found between the (ΔSM) values estimated by Landau theory and those obtained using the classical Maxwell relation. In order to estimate the spontaneous magnetization Ms pont(T), we used the mean-field theory to analyses the (ΔSM) vs. M2 data. The obtained Ms pont(T) values are in good agreement with those found from the classical extrapolation from the Arrott plots(H/M vs. M2), confirming that the magnetic entropy is a valid approach to estimate the spontaneous magnetization in our system. At a relatively low magnetic field, a phenomenological model has been used to estimate the values of the magnetic entropy change. The results are in good agreement with those obtained from the experimental data using Maxwell relation.