Modeling exchange bias in thin films and nanostructures

We report on results obtained with a mean-field type calculation for an exchange bias (EB) system consisting of a ferromagnetic (FM) monolayer in contact with an antiferromagnetic (AFM) thin film. Both the bias field H_eb and the coercivity H_c are calculated. The AFM layer is magnetically diluted and different degrees of dilution ranging from zero to 50% are considered. The results obtained for the bias fields are in qualitative agreement with those obtained previously with Monte Carlo simulations. For the coercivity H_c we find in agreement with experiments a strong maximum around the blocking temperature where H_eb vanishes. This maximum is also present for zero dilution of the AFM for which the EB field must vanish, since we are considering ideal compensated interfaces. We also study the EB of a system consisting of FM nanodots in contact with an AFM film systematically, showing the decreasing influence of the domains in the AFM layer as the lateral size of the FM dots are below the average size of the AFM domains.