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We report a study of the critical phenomena of perovskite-manganite compound La 0.6 Pr 0.1 Sr 0.3 MnO 3 around the Curie temperature. Experimental results based on magnetic measurements using Banerjee criterion reveals that the sample exhibits a second-order paramagnetic–ferromagnetic transition. The critical behavior analysis and the Kouvel–Fisher method suggests that the critical phenomena around the critical point can be correctly described by the 3D-Heisenberg model. Critical exponents were estimated and found β =0.354±0.009 and γ =1.264±0.035 at T C =325.5±0.443 K. The critical exponent δ is determined separately from the isothermal magnetization at T C and evaluated to δ =4.934±0.0004. These critical exponents obey the Widom scaling relation δ =1 ‏ + γ / β . Based on the critical exponents, the magnetization–field–temperature ( M–H–T ) data around T C collapses into two curves obeying the single scaling equation M ( H , ε ) = | ε | β f ± ( H / | ε | β + γ ) where ε =( T−T C )/ T C is the reduced temperature. [ABSTRACT FROM AUTHOR]

The compositional dependence of the magnetic and magnetocaloric properties of LaPrBaMnO (LPBMO) and LaPrBaMnFeO (LPBMFO) were investigated. Polycrystalline samples were prepared by the standard solid-state reaction method. Temperature-dependent magnetization measurements and Arrott analysis reveal second-order ferromagnetic transitions in both samples with Curie temperature increasing with doping iron from 94 K for LPBMO to 277 K for LPBMFO. Magnetic entropy change $$ | {\Delta S_{\text{M}} } | $$ was calculated by applying the thermodynamic Maxwell equation to a series of isothermal field-dependent magnetization curves. However, the analysis of the magnetocaloric effect (MCE) using Landau theory of phase transition shows that the contributions to the free energy from the presence of ferromagnetic clusters are strongly influencing the MCE by coupling with the order parameter around the Curie temperature. [ABSTRACT FROM AUTHOR]

Abstract: The La0.6Pr0.1Sr0.3Mn1−x Fe x O3 (x=0, 0.1, 0.2 and 0.3) samples have been elaborated by the solid-state reaction method. X-ray powder diffraction shows that all the samples crystallize in a rhombohedric phase with space group. The variation of magnetization as a function of temperature and applied magnetic field was carried out. The samples for x=0 and 0.1 exhibit a FM–PM transition at the Curie temperature T C, however, for x=0.2 and 0.3 exhibit an AFM–PM one at the Neel temperature T N, when the temperature increases. A magneto-caloric effect has been calculated in terms of isothermal magnetic entropy change. A large magneto-caloric effect has been observed, the maximum entropy change, , reaches the highest value of 3.28J/kgK under a magnetic field change of 5T with an RCP value of 220J/kg for La0.6Pr0.1Sr0.3MnO3 composition, which will be an interesting compound for application materials working as magnetic refrigerants near room temperature. [Copyright &y& Elsevier]