The effect of nonmagnetic dilution in metallic antiferromagnets (AFMs) on the exchange bias (EB) has been investigated from a structural, magnetic, and Monte Carlo simulation point of view in bilayers of CoFe/(IrMn)1-xCux. Dilution by Cu atoms throughout the volume of the AFM IrMn gives rise to an enhanced EB field (HEB) for 5 K

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The irreversible thermoremanent magnetization (m irr TRM ) of a sole, magnetically diluted epitaxial antiferromagnetic Co 1−y O(100) layer is determined by the mean of its thermoremanent magnetizations (m TRM ) at positive and negative remanence. During hysteresis-loop field cycling, m irr TRM exhibits successive reductions, consistent with the training effect (TE) of the exchange bias measured for the corresponding Co 1−y O(100)/Co(1120) bilayer. The TE of exchange bias is shown to have its microscopic origin in the TE of m irr TRM of the magnetically diluted AFM.

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The effect of enhancing exchange bias (EB) by nonmagnetic defects in high-anisotropy insulating antiferromagnets (AFMs), such as CoO, is tested in low-anisotropy metallic AFMs, such as γ-Fe50Mn50. The temperature dependence of EB and coercivity of Ni80Fe20∕(Fe50Mn50)1−xCux ferromagnetic/antiferromagnetic (FM/AFM) bilayers, where x is the defect concentration in the AFM, is investigated. We show both by experiment and Monte Carlo simulations that the EB presents a maximum as a function of x. However, the increasing role of thermal relaxation of the AFM spin structure leads to a decrease of the FM/AFM blocking temperature with increasing x. The simulations indicate the occurrence of a fast thermal relaxation in the AFM at temperatures below the isolated spin blocking temperature. This result explains the experimental observation that with increasing x the temperature dependence of the FM/AFM coercivity changes from a monotonous decrease to a nonmonotonous dependence, exhibiting a maximum near the blocking temperature.