Evolution of Griffith phase in hole doped double perovskite La_2−xSr_xCoMnO₆(<i>x</i>= 0.0, 0.5, and 1.0)

Abstract

We report on the magnetic properties of hole doped La2−xSrxCoMnO6 (x = 0.0, 0.5, and 1.0) double perovskite synthesized by the low-temperature sol-gel method. X-ray photoelectron spectroscopy (XPS) analysis reveals the increase of the number of Mn3+ and Co3+ ions with Sr content. The reduction in magnetic moment with the increase in Sr content is assigned to the increase of antiferromagnetic (AFM) phases. Detailed analysis of zero field cooled dc magnetic susceptibility as a function of temperature for the samples reveals the features of Griffiths-like singularity. Second harmonic nonlinear ac magnetic susceptibility (χ2) also demonstrates the aspects of Griffiths phase (GP) singularity above the ferromagnetic Curie temperature for all the samples. The value of the exponent of the GP (λ < 1) is found to decrease with Sr substitution in the La site, and it is not related to the structural disorder originating from the Jahn–Teller active Mn3+ions. Hence, it is concluded that with increasing Sr content, the nucleation of GP singularity is supressed due to the increase in the AFM phase volume fraction.