Effect of Non-magnetic Ti⁴⁺ Ion Doping at Mn-site on Magnetocaloric Properties and Critical Behavior in AMn_1-xTi_xO₃ (0 ≤ x ≤ 0.2) Compounds

Abstract

In this paper, we present a thorough study for the critical behavior of AMn_1-xTi_xO₃ (A = La_0.5Pr_0.2Sr_0.3, 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(T_C,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-$\Delta S_{M} = a\left( H \right)^{n}$ power law, where the exponent n values ranging between 0.68 and 0.74 are close to those obtained from the theoretical relation $n(T_C) = 1 + \left(\left( \beta - 1\right)/\left(\beta + \gamma \right)\right)$. 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 (∆S_M vs. M²) are in good agreement with those obtained from the classical extrapolation of Arrott curves (H/M vs. M²).