Effect of Mn Interface Doping in Polycrystalline Exchange Bias Thin Films

We report on the effect of 0-5 monoatomic layers of Mn deposited at the interface of a CoFe/IrMn polycrystalline thin film. All samples were produced via sputtering. Thermal activation measurements were carried out using the well-established York Protocols. In conjunction with grain size analysis performed on each sample the value of the antiferromagnet (AF) anisotropy K_AF was found. An increase in exchange bias H_ex was found in the case of 1-2 atomic layers, however a sharp decrease was seen with the addition of further layers. There was no change in the median grain diameter D_M , or in the median blocking temperature (T_B ), and consequently K_AF, with the addition of Mn. However in the samples with the Mn interfacial layers H_ex was found to increase by up to 100 Oe when the setting field H_set, was varied from 5 to 20 kOe.