Numerical study of the exchange bias effects in magnetic nanoparticles with core/shell morphology

We have used the Monte Carlo simulation technique to investigate the effect of an antiferromagnetic shell on the exchange bias and the coercive fields of composite magnetic nanoparticles with core/shell morphology. We find that the exchange bias field depends mainly on the structure of the interface and less on its size, while the coercive field depends mainly on the interface size. A reduction of the core thickness for a given particle size results in an increase of both exchange bias and coercive fields. An increase of the shell thickness for a given core size enhances the exchange bias field and reduces the coercive field. An increase in the strength of the interface and shell-exchange coupling constant results in an increase of the exchange bias field and a reduction of the coercive field. In all cases the exchange bias field has a stronger temperature dependence than the coercive field. Our results are in good agreement with experimental findings.