Interfacial Magnetic Coupling in NiFe2O4–CoO Nanosystems with Core–Satellite Morphology

Achieving precise control over nanostructures is the key to unlocking new functionalities in magnetic materials. Here, we present the synthesis of a NiFe2O4-CoO (NFO-CO) nanocomposite, where CO selectively nucleates onto spinel NFO seeds, forming distinctive core-satellite architectures. Structural analysis confirms that NFO retains its crystallinity, while TEM captures the chemical contact between NFO cores and CO satellites, which causes a remarkable enhancement in coercivity and a pronounced exchange bias effect, revealing strong interfacial interactions, in agreement with Monte Carlo simulations. Our findings highlight the significance of tailoring the morphology for material design in magnetism.