Exchange coupling of (Mn-Ir,Fe-Mn)/Ni-Fe-Co and Ni-Fe-Co/(Mn-Ir,Fe-Mn) films formed by ion beam sputtering

We investigated exchange couplings between magnetic layers and antiferromagnetic layers in (Mn-Ir, Fe-Mn)/Ni-Fe-Co and Ni-Fe-Co/(Mn-Ir, Fe-Mn) films formed by ion beam sputtering. We changed a stacking order between the magnetic layers and antiferromagnetic layers, and the thickness of the antiferromagnetic layers. In both the Fe-Mn/Ni-Fe-Co and the Ni-Fe-Co/Fe-Mn films, high exchange bias fields applied to the Ni-Fe-Co layers were observed, when the thickness of the Fe-Mn layer was 10-20 nm. When the Mn-Ir layers were formed on the Ni-Fe layers, the high exchange bias fields were also observed. However, the exchange bias fields were very low when the Mn-Ir layers were formed under the Ni-Fe layers. The decrease of the exchange bias field was caused by the deterioration of the (111) texture near the top surface which faces the Ni-Fe layer in the Mn-Ir layer.