Exchange-bias phenomena and modeling in nanocrystalline powders of MnO/FeCo and NiO/Fe -: art. no. 10K103

An approach towards the modeling of the magnetic behavior in heterogeneous systems of exchange-coupled antiferromagnetic (AF) and ferromagnetic (FM) particles with composition (AF)(x)+(FM)(1-x) is presented. The model is based on the Preisach hysteresis model and correctly predicts the correlation between the exchange-bias field and the mean grain size of the material, as established from the measurements of the hysteresis loops in mechanically alloyed (MnO) + (alpha-FeCo). The model was also used to calculate the unidirectional anisotropy interface energies in both this and (NiO)(x)+(alpha-Fe)(1-x) system; in the latter case, the predicted value was in full agreement with that reported for antiferromagnetic layers of NiO. (c) 2005 American Institute of Physics.