Memory effects in systems of nanoparticles: A Preisach model

The relaxation dynamics of Preisach superpositions of thermally activated, bistable elements are shown to exhibit aging and memory effects in response to certain field- and temperature-cycling protocols, which are reminiscent of those observed in spin glasses, but which are not a consequence of collective freezing. Model simulations are able to replicate memory effects observed in a thin film of Fe nanoparticles embedded in glass.