Quantitative description of the azimuthal dependence of the exchange bias effect

While the principal features of the exchange bias between a ferromagnet and an antiferromagnet are believed to be understood, a quantitative description is still lacking. We show that interface spin disorder is the main reason for the discrepancy of model calculations versus experimental results. Taking into account spin disorder at the interface between the ferromagnet and the anti ferromagnet by modifying the well known Meiklejohn and Bean model, an almost perfect agreement can be reached. As an example this is demonstrated for the CoFe/IrMn exchange biased bilayer by analysing the azimuthal dependence of magnetic hysteresis loops from MOKE measurements. Both exchange bias and coercive fields for the complete 360 degrees angular range are reproduced by our model.