Surface effects on the magnetic behaviour of nanoparticles with core/shell morphology

We study the influence of the surface on the hysteresis behaviour of nanoparticles with core/shell morphology at an atomic level. We use a model that explicitly takes into account the dynamics of the core, interface and surface regions using the Metropolis Monte Carlo simulation algorithm. The presence of uncompensated spins ( Nu ) and the surface spins' canting strongly influence the magnetic response of antiferromagnetic nanoparticles. The strength of the surface anisotropy in this case determines the behaviour of the temperature dependence of the coercive field. In ferrimagnetic nanoparticles the magnetization and coercivity depend on the details of the surface.