Response of iron oxide on hetero-nanostructures of soft and hard ferrites

Core-shell nanostructures of Zinc and Cobalt ferrites synthesized by solution evaporation route are observed to perform novel magnetic response. The structural and morphological analyses of ZnFe2O4−core/Fe3O4−shell and CoFe2O4−core/Fe3O4−shell nanoparticles (NPs) are confirmed with X-ray diffractometer (XRD) and high resolution transmission electron microscopy (HRTEM). Physical properties measurement system (PPMS) investigations at room temperature reveal that the synthesized core-shell NPs (∼8 nm in diameter) are in super-paramagnetic state. The coercivity of ZnFe2O4/Fe3O4 is much lower than that of CoFe2O4/Fe3O4 NPs (e.g., at 5 K: Hc = 0.6kOe for ZnFe2O4/Fe3O4 and Hc = 18kOe for CoFe2O4/Fe3O4. Fe3O4 is preferable to reduce magnetic hardness for Zinc ferrite and enhance for Cobalt Ferrite.