Ion-beam bombardment has been established as an effective way to tune the microstructure and thus modify the magnetic anisotropy of thin film materials, leading to certain remarkable magnetic properties. In this work, we investigated a Ni 80 Fe 20 /α-Fe 2 O 3 bilayer deposited with a dual ionbeam deposition technique. Low-energy argon ion-beam bombardment during the α-Fe 2 O 3 deposition led to a decline of crystallinity and interfacial roughness of the bilayer, whereas the grain size distribution remained essentially unchanged. At low temperature, the coercivity exhibited a pronounced decrease after the bombardment, indicating that the effective uniaxial anisotropy in the ferromagnetic layer was dramatically reduced. Such reduction in uniaxial anisotropy was likely attributed to the irreversible transition in the α-Fe 2 O 3 grains caused by the ion-beam bombardment, which subsequently modified the anisotropy in the Ni 80 Fe 20 layer. The bombarded bilayer also exhibited a larger ΔM FC-ZFC compared to the unbombarded bilayer, which indicated a stronger exchange coupling between the ferromagnetic layer and the antiferromagnetic layer.

We have investigated the magnetism of NiFe/CoO/Co trilayers with different CoO spacer thicknesses. The dependence of the coercivity (H c) and exchange bias field (H ex) on the CoO thicknesses indicated that different pinning strengths from the CoO were acting on the top NiFe and bottom Co layers, respectively. DC susceptibility indicated the different interlayer coupling energies and showed that the anisotropy of CoO layer strongly affected the temperature dependence of the magnetization. V

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