Density functional theory studies of Fe and Mn substituted CoCr2O4
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2017
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Abstract
Spinel compound CoCr2O4 is found to be a promising multiferroic material as it exhibits switchable electric polarization under reversal of magnetic field. In a bid to enhance the functional properties of CoCr2O4 , recent experiments attempted substitution of Cr by a another magnetic atom. Substitution of Fe and Mn in place of Cr led to fascinating phenomena like temperature and composition dependent magnetic compensations, magnetostrsiction effects, composition dependent tunable exchange bias which are not observed in pristine CoCr2O4. The experimental results on various thermal, structural and magnetic properties in Fe and Mn substituted CoCr2O4 implied that there can be significant cation disorder present in these systems which renormalizes the magnetic exchange interactions and in turn is responsible for the anomalous behavior of the physical quantities with changes in the compositions of the system. In order to gain fundamental understandings into various effects like the cation disorder, the crystal fields, the magnetic exchange interactions and their interplay, the electron-electron correlations, the spin-lattice coupling on the properties of these systems and thus provide interpretations of the available experimental results, in this dissertation.
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Supervisor: Subhradip Ghosh
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PHYSICS