Correlation between critical behavior and magnetocaloric effect for La0.8-x·xNa0.2-x·xMnO3 (x=0 and 0.1) compounds. (April 2019) - Ameur, N.
Abstract: The critical behavior of manganite perovskite type La0.8-x·x Na0.2-x·x MnO3 (with x = 0 and 0.1) was studied based on the experimental magnetic measurements in the paramagnetic ferromagnetic transition region using different techniques such as the modified Arrott plot, the Kouvel-Fisher method and critical isothermal analysis. Experimental results revealed that the two samples show a second-order magnetic phase transition. The deduced critical exponents are close to a 3D Ising model for La0.8 Na0.2 MnO3 and a 3D tricritical mean field model for La0.7·0.1 Na0.1·0.1 MnO3 . The reliability of these critical exponents was confirmed by the Widom scaling relation and the universal scaling hypothesis. Moreover, an excellent agreement was found between the spontaneous magnetization determined from the entropy change and from the extrapolation of the modified Arrott plots, confirming the universal behavior of the magnetocaloric effect in these systems. Highlights: The β, γ and δ critical exponents are determined with various techniques. We deduce from (RS) that the ising mean-field model is the most adequate model for La0·8 Na0.2 MnO3 and the tricritical mean-field model for La0.7·0.1 Na0.1·0.1 MnO3 . Correlation between the critical behavior and the magnetocaloric properties to be determined.