Effect of Non-magnetic Ti4+ Ion Doping at Mn-site on Magnetocaloric Properties and Critical Behavior in AMn1-xTixO3 (0 ≤ x ≤ 0.2) Compounds

In this paper, we present a thorough study for the critical behavior of AMn1-xTixO3 (A = La0.5Pr0.2Sr0.3, x = 0.0 and 0.2) polycrystalline samples by analysing their isothermal magnetization data using various technique such us modified Arrott plots, Kouvel-Fischer method, and critical magnetisation isotherms M(TC,H). The critical exponent values for the undoped compound allowed us to assign a mean field universality class with long-range interactions (β = 0.509,γ = 1.094,δ = 3.14). The non-magnetic Ti-substitution does not affect the class of universality. The analysis shows that the critical exponents of all compounds were close to those of the mean field model with long-range interaction. The field dependence of the magnetic entropy change is also analyzed using-ΔSM=aHn\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\Delta S_{M} = a\left( H \right)^{n}$$\end{document} power law, where the exponent n values ranging between 0.68 and 0.74 are close to those obtained from the theoretical relation n(TC)=1+β-1/β+γ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$n(T_C) = 1 + \left(\left( \beta - 1\right)/\left(\beta + \gamma \right)\right)$$\end{document}. The second-order nature of the magnetic phase transition has been confirmed by constructing the universal magnetic entropy change curves. The spontaneous magnetization values determined using the magnetic entropy change (∆SM vs. M2) are in good agreement with those obtained from the classical extrapolation of Arrott curves (H/M vs. M2).