Experimental and Theoretical Investigation of Cation Site Occupation and Magnetic Ordering in Co-Ferrite Spinels

Phase pure cobalt ferrite of spinel structure (CoFe
2
O
4
) is experimentally synthesized using bulk powder processing methods and characterized using neutron diffraction methods to quantitatively characterize cation site occupation, magnetic moment, and magnetic ordering as a function of temperature. Novel computational techniques based upon a combination of density functional theoretical calculation, machine learning, and Monte Carlo methods are applied to calculate the same quantities for direct comparison with experiments. The obtained results show excellent agreement, and the combination of experimental and theoretical methods enables the unambiguous extraction of exchange bond energies between A-A, B-B, and A-B sites in the spinel structure with excellent agreement to theoretical predictions, as compared to traditional empirical fitting methods using average magnetization as a function of temperature. The proposed methods offer an opportunity to further explore spinel ferrite systems for a deeper understanding of bonding and exchange interactions within these complex and interesting ferrimagnetic systems.