Determination of the spontaneous magnetization by analysis of the magnetic entropy change in La0.40Nd0.30Sr0.30Mn0.70Cr0.30O3

The magnetic phase transition and magnetic entropy change (−ΔSM) in the La0.40Nd0.30Sr0.30Mn0.70Cr0.30O3 perovskite were investigated by measuring the magnetization as a function of temperature. The ferromagnetic transition temperature TC and the critical exponents β and γ, determined by analyzing the Arrott plots, are found to be TC = 191 K, β = 0.433, γ = 1.053 and δ = 3.486. These values for the critical exponents are close to the mean-field values. In order to estimate the spontaneous magnetization Ms(T) at a given temperature, we use a process based on the analysis, in the mean-field theory, of the magnetic entropy change (−ΔSM) versus the magnetization data. An excellent agreement is found between the spontaneous magnetization determined from the entropy change ((−ΔSM) vs. M2) and the classical extrapolation from the Arrott curves (μ0H/M vs. M2), thus confirming that the magnetic entropy is a valid approach to estimate the spontaneous magnetization in this system and in other compounds as well.