Structural, magnetic, magnetocaloric and critical properties of La0.9Ba0.1MnO3 manganite

Polycrystalline La0.9Ba0.1MnO3 (LBMO) manganite samples are synthesized by usual solid state reaction technique. X-ray powder diffraction at room temperature indicates that our samples crystallize in the rhombohedral structure with an R3¯c space group. Magnetocaloric and critical behavior of the sample is probed through temperature and magnetic field dependent magnetization measurements. The compound shows paramagnetic-ferromagnetic (PM-FM) transition at critical temperature (TC) of 280 K and the nature of this transition is of second order. The deviation in the inverse of susceptibility versus temperature plot from Curie-Weiss law near TC unveiled the presence of Griffiths phase (GP) at TG = 292 K with susceptibility exponent λ = 0.3. The presence of Griffiths phase (GP) proves the existence of ferromagnetic clusters in the paramagnetic domain. Having second order phase transition sample shows a maximum magnetic entropy change (ΔSMmax) of 0.665 J/kg K for the magnetic field change of 4 Tesla. The sample also exhibits high relative cooling power (RCP) of 28.83 J/kg against this field. The critical behavior of second order phase transition in this sample is analyzed using Modified Arrott plots (MAP), Kouvel Fisher (KF) and critical isotherm analysis method. The estimated critical exponents of the sample are β ≈ 0.3, γ ≈ 1.32 and δ ≈ 5.1. These values of the critical exponents are also verified by scaling equations of state. Further the change in magnetic entropy (ΔSM) versus applied field obeys the power law ΔSM = (μoH) n with exponent value n = 0.55 at TC = 280 K.