Influence of grain size and sintering temperature grain size on the critical behavior near the paramagnetic to ferromagnetic phase transition temperature in La_(0.67)Sr_(0.33)MnO_3 nanoparticles

摘要

Graphical abstractScaling plots indicating two universal curves below and aboveTC. Inset show the same plots on a log-log scale.Display OmittedHighlights•The effect of grain size and sintering temperature on the critical properties is studied.•The calculated critical exponents are satisfied with the scaling theory.•The β, γ, and δ, found forL6,L8andL10, are consistent with the Mean-field theory.•ForL12, the values of the critical exponents are similar to the (3D) Heisenberg model.•The reduction of grain size strongly influences the universality class.AbstractWe have undertaken a systematic study of critical behavior in La0.67Sr0.33MnO3nanoparticles, sintered at different temperatures (L6,L8,L10andL12sintered at 600 °C, 800 °C, 1000 °C, 1200 °C respectively), by magnetization measurements. The critical exponents are estimated by various techniques such as the Modified Arrott plot, Kouvel–Fisher plot and critical isotherm technique. Compared to standard models, the critical exponents are close to those expected by the Mean-field model (with β = 0.5 γ = 1, andδ = 3) for (L6,L8, andL10) samples and by the (3D) Heisenberg model (β = 0.365, γ = 1.336 andδ = 4.80) forL12sample. We conclude that the reduction of grain size strongly influences the universality class.