Exchange-Coupled FeNi–X (X CuO, NiO, and CoO) Nanocomposites Prepared Via Ball Milling

Exchange-coupled magnetic nanocomposite powders were obtained by mechanically milling ferromagnetic (FM)-antiferromagnetic (AFM) powders. A shift in the field-cooled (FC) hysteresis loop and the coercivity enhancement of the FM phase ensuing from exchange bias anisotropy was observed. The blocking temperature (T_B) in all composites was found to be much lower than the Neel temperature (T_N) of the AFM phases. A model based on Preisach hysteresis was used to calculate the interfacial energy between FM and AFM particles. The calculated interfacial energies were highest for FM-CoO and lowest for FM-CuO composites. These values are in good agreement with those reported for polycrystalline AFM thin films