Ferri-/Antiferromagnetic Heterostructures: A Case Study of the Fe ₃ O ₄ /NiO Interface

We investigate the interfacial spin structure of prototypical room-temperature antiferromagnet NiO, epitaxially grown on Fe3O4(111)/Ru(0001). The heterostructures were fabricated using high-temperature oxygen-assisted molecular beam epitaxy on a Ru single-crystal substrate. A comprehensive structural characterization was carried out by low-energy electron microscopy and diffraction, while chemical and magnetic properties were probed using photoemission electron microscopy combined with synchrotron radiation. Specifically, X-ray absorption spectroscopy and X-ray magnetic circular/linear dichroism enabled nanoscale analysis of the magnetic ordering. Although bulk NiO is antiferromagnetic and exhibits no net magnetization, hence showing no circular dichroism, interfacial interactions at the Fe3O4/NiO boundary can significantly influence the magnetic domain configuration in NiO, leading to emergent interfacial magnetic behavior. By resolving the spin axis orientation of NiO with nanometer precision and correlating it with the ferrimagnetic domain structure of Fe3O4, we provide new insight into the interfacial coupling mechanisms.