Marwène Oumezzine;Mohamed Baazaoui;Sobhi Hcini;Mohamed Oumezzine;
The critical behaviour of the manganese perovskite La0.67Ba033Mn0.95Fe0.05O3 around the paramagnetic-ferromagnetic phase transition, were investigated through various techniques such as modified Arrott plot, Kouvel-Fisher method and critical isotherm analysis based on the data of static magnetic measurements recorded around the Curie temperature T C . The experimental results reveal that the sample undergoes a second-order phase transition. From the derived values of the critical exponents (β=0.512, γ=1.026), we conclude that La0.67Ba033Mn0.95Fe0.05O3 belongs to the mean-field theory with long-range interaction. On the Basis of these critical exponents, the magnetization, field and temperature data around T C collapse onto two curves obeying the single scaling equation M(H,ε)=εβ f ± (H/εβ+γ). Moreover we have investigated the validity and usefulness of the theoretical modeling in our compound La0.67Ba033Mn0.95Fe0.05O3 based on the landau mean-field analysis of the magnetic entropy change (SM) versus the magnetization data. Results obtained through this approach are compared to those obtained from extrapolation of the Arrott curves. An excellent agreement was obtained between this approach with the one obtained from the extrapolation of the Arrott curves. By investigating the field dependence of S M and RCP, it was possible to evaluate the critical exponents of the magnetic phase transitions. Their values are in good agreement with those obtained from the critical exponents using a modifiedArrott method.
Magnetocaloric effect, Relative cooling power, Magnetic entropy, critical phenomena
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