Magnetocaloric effect and critical behavior of Nd1-3xBaxCaxSrxMnO₃ (0.066 ≤ x ≤ 0.11) manganites: optimization of doping for enhanced refrigerant performance

This study investigates the magnetic and magnetocaloric properties of Nd_1-3xBa_xCa_xSr_xMnO₃ (\(0.066 \le x \le 0.11\)) manganites through experimental analysis and numerical simulations. Using the Arrott–Noakes equation and the Landau model, critical exponents (γ, β) were determined to be (1; 0.43), (1.06; 0.39), and (1; 0.88) for Nd_1-3xBa_xCa_xSr_xMnO₃ with x = 0.066, 0.1, and 0.11, respectively, via the Modified Arrott Plot and Kouvel–Fisher method, revealing deviations from conventional universality classes. Numerical simulations of magnetization behavior showed strong agreement with experimental data. Magnetocaloric effect (MCE) analysis demonstrated an enhanced magnetic entropy change (\(- \Delta S_{M}\)) with increasing Ba, Ca, and Sr doping, leading to improved refrigeration efficiency, particularly at x = 0.1. The present samples exhibit considerable maximum magnetic entropy change of \(\left| {\Delta S_{M}^{max} } \right|\) of 5.24, 4.15 and 2.65 J·kg⁻¹·K⁻¹ with Temperature-Averaged Entropy Change TEC (3 K) of 4.77, 4.06 and 2.61 J·kg⁻¹·K⁻¹ under 5 T magnetic field for Nd_1-3xBa_xCa_xSr_xMnO₃ with x = 0.066, 0.1 and 0.11, respectively. These findings provide insights into optimizing doping strategies for enhanced magnetocaloric performance in manganite-based refrigerants.