Critical Behavior and Magnetocaloric Properties of LPSMO Nanocrystals via Landau Theory

Abstract

This study presents a computational methodology that combines the Landau theory with the Arrott–Noakes equation. Through an innovative formulation, simulations are performed to investigate the magnetic entropy change, $-\mathrm{\Delta }{\mathrm{S}}_{\mathrm{M}}$, in a disordered ferromagnetic system. The theoretical framework is applied to analyze the critical behavior using experimental isothermal magnetization data $M(H,T)$ of (La_1–xPr_x)_0.7Sr_0.3MnO₃ (x = 0, 0.2, 0.4, 0.6, 0.8, and 1) nanocrystalline perovskites. Initially, the critical exponents ($\gamma$ and $\beta$) of these materials are determined. It is observed that the magnetic properties of the studied compounds near the phase transition deviate from the mean-field model. These critical exponents are then used to simulate isothermal $M(H,T)$ and $-\mathrm{\Delta }{\mathrm{S}}_{\mathrm{M}}(\mathrm{H},\mathrm{T})$ curves.