Structural, magnetic, magnetocaloric and critical behavior investigations of La0.65Dy0.05Sr0.3MnO3 manganite

Abstract

In the present work, we report a detailed study of the structural, magnetic, magnetocaloric properties as well as critical behavior in La0.65Dy0.05Sr0.3MnO3 ceramic synthetized by the conventional solid-state reaction. Rietveld refinement of the X-ray diffraction patterns indicates that our sample is pure single phase adopting the rhombohedral structure (R3¯c space group). Temperature dependence of magnetization exhibits a paramagnetic (PM) to ferromagnetic (FM) transition at Curie temperature TC = 265 K. Close to this transition, the magnetic entropy change reaches a maximum of about 2.19 J/kgK and the relative cooling power (RCP) value is of 241 J/kg, when a magnetic field of 5 T is applied. Additionally, Banerjee's criteria, Landau theory and the universal behavior of phase transitions were also studied to assess magnetic phase ordering in this material, such investigations indicate that the phase transition from the PM to FM states is of second order. Through various techniques such as modified Arrott plot (MAP), Kouvel–Fisher (KF) method and critical isotherm (CI) analysis, the critical parameters (TC, β, γ, and δ) have been determined. The estimated critical exponents (β = 0.515, γ = 1.082 and δ = 2.932 at TC = 264.85 K) are found to be close to the mean-field model. This proves the existence of long range ferromagnetic interactions in this system. The reliability of the critical exponent values was confirmed by the Widom scaling relation and the universal scaling hypothesis.