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 TC. With the Modified Arrot plot method, the critical exponents were found to be β = 0.254, γ = 0.934 at TC = 308.9 K and β = 0.347, γ = 1.29 at TC = 287.8 K for xTi = 0.0 and xTi = 0.05 samples, respectively. Thus, the magnetic interactions satisfied with the prediction of 3-D Tricritical mean field model for xTi = 0.0 and the Heisenberg model forxTi = 0.05. Therefore, the universality class was affected by Ti doping. This result was confirmed by the Kouvel-Fisher method which gave values of β = 0.269, γ = 1.024 at TC = 309.0 K and β = 0.356, γ = 1.31 at TC = 288.3 K for xTi = 0.0 and xTi = 0.05 samples, respectively. These values were checked by the Widom’s scaling equation δ = 1 + γ/β and the Stanley’s scaling equation MHε=εβf±Hεβ+γ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ M\left(H,\varepsilon \right)={\varepsilon}^{\beta }{f}_{\pm}\left(\frac{H}{\varepsilon^{\beta +\gamma }}\right) $$\end{document}. 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, ∆SM ∝ Hn.