Magnetization reversal, critical behavior, and magnetocaloric effect in NdMnO3: The role of magnetic ordering of Nd and Mn moments.

The magnetic properties, critical behavior, and magnetocaloric effect of perovskite NdMnO₃ are studied. The Nd ordering is induced by the Mn ferromagnetic component with antiferromagnetic coupling with each other and then magnetization reversal occurs due to Mn moments reorientation induced by the ordering Nd moments, which explains the phenomenon of negative magnetization at low temperatures. The critical behavior of NdMnO₃ is studied using Kouvel–Fisher and self-consistent methods. The results show that the Kouvel–Fisher method is reliable and critical exponents are coming out as β = 0.462 for T_C = 11.15 K, γ = 1.041 for T_C = 11.42 K, δ = 3.252 by critical isotherm analysis. Magnetic exchange distance may decay as J (r) ≈ r − 4.563 , that is, somewhere between the three-dimensional Heisenberg model and the mean field model. Remarkably, three temperature transitions and the corresponding three extremum values including positive and negative entropy change are observed in NdMnO₃, which is different from previous reports on NdMnO₃. A positive entropy change as 3.82 J/kg K at 10–15 K for μ₀ΔH = 50 kOe and a negative entropy change as −0.557 J/kg K at around 8 K for μ₀ΔH = 5 kOe are found, which can be put down to a fast magnetization change of NdMnO₃ because of the Nd moments ordering and Mn moments reorientation. Besides, an entropy change of 1.22 J/kg K is found for μ₀ΔH = 50 kOe at 80–85 K, which is corresponding to the Mn ferromagnetic ordering temperature. The relative cooling power of NdMnO₃ reaches 105.9 J/kg, making it a promising candidate in the field of magnetic refrigeration. [ABSTRACT FROM AUTHOR]