In this paper, we propose a novel and efficient method to estimate spontaneous magnetization from the isothermal magnetic entropy change \(-\Delta {\text{S}}_{\text{M}}(\text{H},\text{T})\) in ferromagnetic materials. The method was applied to the La0.7(La-Ce)0.3Fe11Al0.5Si1.5 (L(L-C)FAS) alloy, which undergoes a second-order ferromagnetic–paramagnetic (FM–PM) phase transition at a Curie temperature of \({\text{T}}_{\text{C}}=\) 211.2 K. Using modified Arrott plots and iterative fitting techniques, we determined the critical exponents as \(\upgamma =1\text{ and}\) \(\upbeta =0.5\) confirming the transition’s consistency with the mean-field model. These exponents were employed to simulate isothermal magnetization \(\text{M}(\text{H},\text{T})\) and \(-\Delta {\text{S}}_{\text{M}}(\text{H},\text{T})\) curves under magnetic fields up to 5 T which closely matched experimental data, indicating the robustness of the model in predicting magnetocaloric behavior in rare-earth intermetallics.
