Magnetic properties of exchanged-coupled nanostructured core–shell particles of CoO@MnFe[formula omitted]O[formula omitted

Abstract

In this work the structural and magnetic properties of nanoparticles of bimagnetic core–shell CoO@MnFe2O4 were reported. The structure and the morphology of the nanoparticles were characterized by X-ray powder diffraction and by transmission electron microscopy. Hysteresis loops were recorded by varying the applied magnetic field (H) in the range ± 85 kOe for several temperature values (T). The T-dependence of the zero-field- and the field-cooling magnetization were investigated from room temperature until 5 K for H = 100 Oe. The coercivity was found to be enhanced to about 2.34 kOe at 5 K while shiftings in the hysteresis loops due to the exchange-bias effect were also observed reaching 472 Oe at 5 K. The blocking temperature for this core–shell nanoparticle system was also found to be ≈ 103 K. The enhancement in the coercivity and the exchange-bias effect are discussed within a model based on the exchange-coupling of the magnetic moments at the core–shell interface.