Exchange bias control in CoFe/IrMn via grain size control

This work reports on the effect of grain size control on the exchange field (HE) for two different CoFe/IrMn exchange bias systems. Data shows that at room temperature the exchange field increases with the grain size. For smaller IrMn grains, HE is dominated by thermal activation in the IrMn layer. A much greater decay in the exchange field for the samples with the smallest grains was observed, confirming that the energy barriers in the IrMn layer are grain size dependent. Results also show that the coercivity is independent of the grain size indicating that coercivity arises due to interfacial effects.