Premium content
Access to this content requires a subscription. You must be a premium user to view this content.
poster
Understanding magnetization reversal mechanisms and exchange interactions in nanostructured cobalt ferrites using first order reversal curves (FORC)
Cubic spinel ferrites are a class of oxides represented by the chemical formula AB2O4 with A and B being divalent and trivalent cations occupying octahedral and
tetrahedral voids. Magnetization arises from superexchange interactions between cations via the oxygen anion. Among these, cobalt ferrites have been shown to undergo spinodal
decomposition to form periodic microstructures at the nm length scale. The resultant changes in magnetic properties have been shown to be dependent on the periodicity and degree of
decomposition. Complex nanostructured microstructures with concomitant spatial variations of intrinsic magnetic properties and magnetic interactions can yield wasp-waisted major
hysteresis loops indicative of multiple magnetization reversal events1. Detailed analysis requires advanced magnetometry techniques, in order to disentangle reversible, irreversible, and
viscous magnetization processes and their dependence on previous magnetic history.
In this work, cobalt ferrite samples have been synthesized using standard powder processing techniques. Different degrees of decomposition have been achieved by varying the annealing
time within the coherent spinodal range. TEM has been used to determine periodicity, degree of decomposition, lattice mismatch and the associated coherency strains between the
decomposed phases. Magnetization processes occurring in these materials have been investigated through vibrating sample magnetometry using major M-H loops and temperaturedependent
magnetization. These measurements have been complemented with non-saturating high-resolution first order reversal curve (FORC) diagrams obtained with different preconditioning
fields, in order to explore magnetic states inaccessible to the major loops. Various switching events corresponding to the features observed in the FORC diagrams have been
identified and correlated with microstructural observations. Finally, a better insight into the nature of the switching events has been obtained with Rayleigh loop measurements along
selected FORCs.
References:
- M. V. Suraj, A. Talaat, B. C. Dodrill, Y. Wang, J. K. Lee, and P. R. Ohodnicki Jr., AIP Advances 12, 035031 (2022)