Interfacial effects on the structural, optical, and magnetic properties of α-Fe₂O₃@RuO₂ core–shell nanostructures

Magnetic nanoparticles composed of transition metal oxide have attracted considerable attention owing to their potential application in information storage, photocatalytic activities, biomedicine, and hyperthermia-based cancer treatment. A key factor underlying these functionalities is the interfacial spin interaction, which governs the magnetic behaviour at the nanoscale by tailoring their physical properties. Here, we present the structural, optical, and magnetic characteristics of a bi-magnetic α-Fe2O3@ RuO2 core-shell nanostructure composed of spindle-shaped α-Fe2O3 decorated with RuO2 nanoparticles. Structural and morphological characterizations confirm the coexistence of both phases in the core-shell system. Optical analyses indicate an enhanced absorption capability of the core-shell nanostructures, beneficial for photocatalytic activity. Additionally, the core-shell system was found to exhibit the Morin transition, similar to core α-Fe2O3. Moreover, our findings also reveal a notable increase in both the coercive field and exchange bias, possibly resulting from the interfacial interaction between the core and shell nanoparticles. This enhancement indicates improved magnetic alignment and unidirectional anisotropy, providing valuable insights into the magnetic properties of core-shell structures and their potential applications in advanced materials.