Memory effects on the magnetic behavior of assemblies of nanoparticles with ferromagnetic core/antiferromagnetic shell morphology

Monte Carlo simulations of the dynamic magnetic behavior of an assembly of ferromagnetic core/antiferromagnetic shell nanoparticles are reported and compared with the experimental results on a system of Co nanoparticles in Mn matrix. Memory effects on low-field zero-field-cooled magnetization curves have been investigated. Our simulations show that the memory effects increase with the concentration and that both the interface exchange coupling and the dipolar interparticle interactions contribute to the observed dynamic behavior. In particular the interface exchange interaction provides an additive source for the frustration of the system resulting in an enhancement of the memory effect. The numerical data reproduce well the experimental results confirming the glassy behavior of the investigated nanoparticle systems.