Magnetic distributions of iron–(nickel zinc ferrite) nanocomposites from first order reversal curve analysis

First order reversal curve measurements offer a powerful approach to quantify the magnetic property distributions in materials. Here, we have used this approach to quantify magnetic property distributions and understand the nano-scale mechanisms contributing to the magnetic anisotropy of Fe-(Ni0.5Zn0.5)Fe2O4 nanocomposites. The Fe-(Ni0.5Zn0.5)Fe2O4 nanocomposite powders were synthesized using a chemical method involving ferrite precipitation and controlled reduction which resulted in the formation of iron nanoclusters within the ferrite. Two samples with a ∼65% and ∼6% iron composition, respectively, were studied. Transmission electron microscopy measurements yielded an average particle size of ∼15 nm (∼65% Fe) and ∼60 nm (∼6% Fe). The magnetizations at 7 T for the synthesized nanocomposites (M7T = 58 Am2 kg−1 for the ∼65% Fe sample and 55 Am2 kg−1 for the ∼6% Fe sample) are close to that of the bulk saturation magnetization (∼60 Am2 kg−1) of (Ni0.5Zn0.5)Fe2O4. This is not typical in these ferrite systems...