Study of Critical Magnetic Behaviour in Nanocrystalline La 0.65 Ce 0.05 Sr 0.3 Mn 1−x Cu x O 3 ( x = 0, x = 0.05 and x = 0.15) Prepared by Pechini Method

The critical bahaviour of La0.65Ce0.05Sr0.3Mn1xCuxO3 (x = 0, x = 0.05 and x = 0.15) manganite prepared by the sol–gel-based Pechini method has been investigated by measuring the magnetization around the Curie temperature, TC. The obtained critical exponents (beta, gamma and delta) have been calculated using the modified Arrott plot and Kouvel–Fisher techniques, scaling hypothesis and critical isotherm analysis. The estimated results for the parent compound and x = 0.05 are in between mean-field and the 3D Heisenberg models. The values of β, γ and δ will shift gradually toward those of the 3D Heisenberg theory when x = 0.15, suggesting that the short-range FM order and magnetic inhomogeneity are favoured in Cu-doped samples. The non-monotonous temperature variation in effective exponents (βeff(ɛ) and γeff(ɛ)) proves the existence of a magnetic disorder in the studied compounds.