Tailoring the Griffiths-like cluster formation in the insulator ferromagnet spin-glass Gd 2 Ni x Co 1 − x Mn O 6 double perovskite

In this paper we present the effects of the composition on structural, vibrational, magnetic, and electronic properties of double perovskite 3d based manganese oxides ${\mathrm{Gd}}_{2}{\mathrm{Ni}}_{x}{\mathrm{Co}}_{1\ensuremath{-}x}\mathrm{Mn}{\mathrm{O}}_{6}$ (GNCMO) powder (for $0lxl1$) prepared by high temperature solid state chemistry. These compounds have a great research interest due to their specific physical properties. We have shown that the synthesized compounds exhibit ferromagnetic interaction between the spins of (${\mathrm{Mn}}^{4+}, {\mathrm{Co}}^{2+}$), and (${\mathrm{Mn}}^{4+}, {\mathrm{Ni}}^{2+}$) cations via oxygen ions and antiferromagnetic interactions between (${\mathrm{Gd}}^{3+}, {\mathrm{Co}}^{2+}$), (${\mathrm{Gd}}^{3+}, {\mathrm{Ni}}^{2+}$) and (${\mathrm{Gd}}^{3+}, {\mathrm{Gd}}^{3+}$) and present a paramagnetic to ferromagnetic phase transition. The paramagnetic Curie-Weiss temperature of GNCMO (${T}_{\mathrm{c}}$) increases from 121to 128K as the nickel content increases from 0.2 to 0.8. Further, temperature dependent inverse magnetic susceptibility $\ensuremath{\chi}{(T)}^{--1}$ shows deviation from Curie Weiss behavior around ${T}_{G}$ which depicts that Griffiths phase already observed in several perovskite compounds. The value of the GP percentage and the exponent of ($\ensuremath{\lambda}l1$) are found to increase as the nickel content increases. The hysteresis curve at $T=20\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ for $x=0.2$ displays a metamagnetic transition explained by the reorientation of the Gd spin moments towards the Mn, Co, and Ni spin moments. The imaginary part of susceptibility ${\ensuremath{\chi}}^{\ensuremath{'}\ensuremath{'}}$ shows a small shift of the peak $\ensuremath{\sim}1\phantom{\rule{4pt}{0ex}}\mathrm{K}$ indicating the presence of spin or cluster glass behavior.