Tailoring the Griffiths-like cluster formation in the insulator ferromagnet spin-glass <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Gd</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>Ni</mml:mi><mml:mi>x</mml:mi></mml:msub><mml:msub><mml:mi>Co</mml:mi><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:mi>Mn</mml:mi><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>6</mml:mn></mml:msub></mml:mrow></mml:math> double perovskite

Abstract

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 $0&lt;x&lt;1$) 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 ($\ensuremath{\lambda}&lt;1$) 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.

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