Structural characterization, magnetic, magnetocaloric properties and critical behavior in lacunar La0.5Eu0.2Ba0.2□0.1MnO3 nanoparticles

Abstract

The lacunar La0.5Eu0.2Ba0.2□0.1MnO3 nanoparticles where □ is a barium deficiency has been prepared using the sol-gel method. The M-T data suggests that the sample undergoes a paramagnetic (PM) to ferromagnetic (FM) transition upon cooling. Deviation of the temperature dependence of inverse susceptibility curves from the Curie Weiss law and less than unity susceptibility exponents indicating the existence of a Griffiths singularity. The magnetocaloric effect and the critical behavior of the sample are systematically studied using bulk magnetization M (H, T) in the vicinity of the Curie temperature. The critical exponents have been obtained using different methods such as modified Arrott plot, critical isotherm analysis and field dependence of magnetocaloric effect. Though the self-consistency and reliability of obtained critical exponents of β = 0.581 ± 0.022, γ = 0.165 ± 0.008 and δ = 3.12 ± 0.03 are verified by the Widom scaling law and scaling equations, the critical parameters do not obey magnetocaloric effect scaling laws, indicating that the nanometer size effect play a significant role on the magnetic phase transition for La0.5Eu0.2Ba0.2□0.1MnO3 nanocrystalline.