Cationic redistribution induced spin-glass and cluster-glass states in spinel ferrite
Sanjib Nayak, Sagar Ghorai, Aneeta Manjari Padhan, Sugato Hajra, Peter Svedlindh, P. Murugavel
Abstract
The effect of the cationic redistribution on the complex spinel structure and magnetic properties were investigated in ${\mathrm{Zn}}_{0.7}{\mathrm{Cu}}_{0.3}{\mathrm{Fe}}_{2}{\mathrm{O}}_{4}$ ferrite. X-ray photoelectron spectroscopy and x-ray diffraction studies revealed that the system exhibits a mixed spinel structure with ${\mathrm{Fe}}^{3+}, {\mathrm{Zn}}^{2+}$, and ${\mathrm{Cu}}^{2+}$ occupying both tetrahedral and octahedral sublattices. The DC magnetization results revealed the absence of long-range magnetic order in the system. Furthermore, the AC susceptibility data analysis using dynamic scaling laws suggests that the system exhibits magnetic relaxation below two different temperatures: (i) a spin-glass--like transition at low temperature ($\ensuremath{\sim}49.2\phantom{\rule{0.28em}{0ex}}\mathrm{K}$) with critical exponent 10.3 and spin-flip time $\ensuremath{\sim}{10}^{\ensuremath{-}11}\phantom{\rule{0.28em}{0ex}}\mathrm{s}$, and (ii) a cluster-glass--like transition at higher temperature ($\ensuremath{\sim}317\phantom{\rule{0.28em}{0ex}}\mathrm{K}$) with critical exponent 4.6 and spin-flip time $\ensuremath{\sim}{10}^{\ensuremath{-}10}\phantom{\rule{0.28em}{0ex}}\mathrm{s}$. The existence of glassy behavior and magnetic memory effects below the spin-glass transition temperature proves that the system is in nonequilibrium dynamical state. The coexistence of spin-glass and cluster-glass along with the thermal hysteresis between these two transitions could widen the technological applications of these systems.