Critical behavior near the paramagnetic to ferromagnetic phase transition temperature in La0.6Sr0.4MnO3 ceramic: A comparison between sol-gel and solid state process

Critical behavior near the paramagnetic (PM) to ferromagnetic (FM) phase transition in La0.6Sr0.4MnO3 ceramics prepared by sol-gel and solid state reaction methods has been systematically investigated. The XRD result coupled with the structural Rietveld refinement method exhibited that all samples crystallized in a rhombohedral structure with a space group of R-3C, which indicated the formation of the perovskite structure of La0.6Sr0.4MnO3. The magnetic data obtained from magnetization measurements indicated a second-order phase transition from PM-FM phase around Curie temperature (TC). Critical exponents, β, γ, and δ values are estimated by various theoretical models such as the modified Arrott plot (MAP), the Kouvel-Fisher plot (KF) and the critical isotherm (CI) techniques. Grain size dependence of the critical behavior of La0.6Sr0.4MnO3 samples with different sizes from nano-scale to mic-scale was detected by fitting the experimental data to the theoretical models.