Estimating spontaneous magnetization from mean field analysis and critical exponents study in La0.6Sr0.4Mn0.9Al0.1O3 compound

The critical behavior of La0.6Sr0.4Mn0.9Al0.1O3 compound was investigated based on the data of static magnetic measurements in the vicinity of its critical temperature TC. Through various techniques such as modified Arrott plot, Kouvel-Fisher method and critical isotherm analysis, the estimated critical exponents were found to be β = 0.45, γ = 1.1, δ = 3.44 at TC =  321 K which is close to Mean-Field model values. The reliability of the critical exponents' values was confirmed by the Widom scaling relation and the universal scaling hypothesis. In order to estimate the spontaneous magnetization MS (T) at a given temperature, we used a process based on the analysis, in the mean-field theory, of the magnetic entropy change (−ΔSM) versus the magnetization data. An excellent agreement was 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). Moreover, the local exponent n was studied in terms of the field dependence of the magnetic entropy change. It was noted that n evolves with field in the entire studied temperature range of our sample, indicating the validity of the mean-field theory for our compound.