A Phenomenological Approach for Predicting Magnetic and Magnetocaloric Properties in the (La2MnNiO6)_x / (La2MnCoO6)_1−x Composite

In this paper, we have investigated the magnetic and magnetocaloric characteristics of a La₂MnNiO₆ composite, in conjunction with La₂MnCoO₆. This composite consists of two phases of double perovskite materials. Employing the mean-field approximation, we successfully modeled how magnetization and the change in magnetic entropy vary with temperature under different magnetic fields in our samples. This phenomenological model helped us also plot the maximum magnetic entropy change (-ΔS_M)_max, full width at half-maximum δT_FWHM, and relative cooling power (RCP). Our analysis has revealed an optimal plateau-type magnetocaloric effect near room temperature, corresponding to a specific composition x between 0.2 and 0.5. Ultimately, this theoretical model lets us predict the magnetic and magnetocaloric behavior of composite materials, providing a foundation for future studies.