The Influence of Sb₂O₃ Phase on Critical Behavior of La_0.6Sr_0.4MnO₃/x(Sb₂O₃) (x = 0, 0.7 and x = 0.18) Ceramic Composites

The critical behavior of La_0.6Sr_0.4MnO₃/x(Sb₂O₃) (x = 0.07 and x = 0.18) compounds has been studied based on the data of static magnetic measurements in the vicinity of its critical temperature T_C. Using various techniques such as modified Arrott plot, Kouvel–Fisher method and critical isotherm analysis, the estimated critical exponents are found to be (β = 0.323, γ = 1.238, δ = 4.862 at T_C = 350.719) and (β = 0.321, γ = 1.243, δ = 4.37at T_C = 365.054), for x = 0.07 and 0.18, respectively; both close to Ising model values. The reliability of critical exponents values was confirmed by the Widom scaling relation and the universal scaling hypothesis. Based on the Harris criterion, we deduced that the disorder in our case is relevant, which can be the cause of the change in the universality class. To study the influence of critical exponents on magneto-caloric effect, the local exponent n was studied in terms of the field dependence of the magnetic entropy change. From the field dependence of RCP and ΔS_M, it was possible to evaluate the critical exponents of the magnetic phase transition. These values are in good agreement with those obtained from the critical exponents using the Kouvel–Fisher plot (K-F).