Interfacial Magnetic Coupling in NiFe ₂ O ₄ –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.