Influence of Non-magnetic Ti4+ Doped on Critical Behavior of La0.55Pr0.1Sr0.35Mn1-xTixO3 (x=0.00, 0.05) Manganites

Our central focus in this research work is upon the study of the effect of lightly Ti4+ doping ions on the critical behavior of La0.55Pr0.1Sr0.35Mn1 - xTixO3 (x = 0.0 and 0.05) perovskite compounds synthesized by the modified sol-gel Pechini method. The two samples underwent a second-order paramagnetic to ferromagnetic transition as temperature decreased. The critical exponents (beta, gamma, and delta) were determined using various methods based all on the measure of magnetization around the Curie temperature T-C. With the Modified Arrot plot method, the critical exponents were found to be beta = 0.254, gamma = 0.934 at T-C = 308.9 K and beta = 0.347, gamma = 1.29 at T-C = 287.8 K for x(Ti) = 0.0 and x(Ti) = 0.05 samples, respectively. Thus, the magnetic interactions satisfied with the prediction of 3-D Tricritical mean field model for x(Ti) = 0.0 and the Heisenberg model forx(Ti) = 0.05. Therefore, the universality class was affected by Ti doping. This result was confirmed by the Kouvel-Fisher method which gave values of beta = 0.269, gamma = 1.024 at T-C = 309.0 K and beta = 0.356, gamma = 1.31 at T-C = 288.3 K for x(Ti) = 0.0 and x(Ti) = 0.05 samples, respectively. These values were checked by the Widom's scaling equation delta = 1 + gamma/beta and the Stanley's scaling equation M. The coupling between critical exponents and magnetocaloric effect was studied by analysis of the field dependence of magnetic entropy change which showed the law dependence, namely, increment S-M proportional to H-n.