Existence of exchange bias and large coercivity in NiFe2O4/CoO core–shell structured nanoparticles

The exchange bias effects of CoFe2O4@NiO nanofibers fabricated by electrospinning

“…The exchange bias effect is that the hysteresis loop of the ferromagnetic(FM) layer deviates from the magnetic field direction after the system is cooled from the Neel temperature (T Neel ) of anti-ferromagnetic(AFM). The systems can consist of permanent magnetic/soft magnetic [1], permanent magnetic/anti-ferromagnetic [2], (FM)/(AFM) [3], ferrimagnetic(FIM)/(AFM) [4] film system [5], core-shell system [6], alloy system [7], etc. In 1956, Meiklejohn and Bean [8] discovered the exchange bias effect, which was due to the spin interaction at the interface of Co nanoparticles covered by CoO, and the hysteresis loop moved along the magnetic field axis after the applied magnetic field cooled.…”