Bi doping effect on the critical behavior and magnetocaloric effect of Pr0.8−xBixSr0.2 MnO3 (x = 0, 0.05 and 0.1)

Highlights: • Critical behavior of Pr_0.8−xBi_xSr_0.2MnO₃ (x = 0, 0.05 and 0.1) is studied. • The magnetocaloric properties of these compounds are also investigated. • A large magnetic entropy change |ΔS_M| is obtained for all prepared samples. • |ΔS_M| curves confirm the second-order PM-FM transition. In this study, we report the effect of Bi doping on the critical behavior and the magnetocaloric properties of Pr_0.8−xBi_xSr_0.2MnO₃ (x = 0, 0.05 and 0.1) structures prepared by sol-gel method. Refined values of the critical exponents β, γ, and δ determined from the modified Arrott plots and Kouvel–Fisher method show that the parent sample is described by the tricritical mean field model whereas the 3D-Ising model is the best model describing doped samples. Consequently, a transition from long-range to short range FM interactions caused by the introduction of Bi in the parent sample can be identified. All samples reveal the presence of some ferromagnetic domains in the paramagnetic phase. In the vicinity of the Curie temperature T_C and for an applied magnetic field of 5 T, the maximum of magnetic entropy change |ΔS_M| decreases from 5.41 J K⁻¹kg⁻¹ for x = 0–3.11 J K⁻¹kg⁻¹ for x = 0.1, respectively. The |ΔS_M| for doped samples exhibits a large broad variation with temperature around T_C as compared with the parent sample. Such effect is substantially advantageous for magnetic refrigeration. Also, the magnetocaloric effect is investigated using Landau theory. A good agreement is obtained between this theory and experimental data, which suggests that electronic interactions and magnetoelastic coupling are at the origin of the magnetocaloric properties of our samples. In addition, we report that |ΔS_M| curves follow the universal law confirming the second-ordered paramagnetic-ferromagnetic transition.