Magnetic Properties of Exchange-Coupled Fe-Ni/Fe22Ni78 Double-Layered Thick Films

We prepared exchange-coupled Fe-Ni/Fe
₂₂
Ni
₇₈
double-layered thick films (24 μm in thickness) using an electroplating method and evaluated their soft magnetic properties. The total Fe content of the double-layered films was varied by the change in the Fe content in Fe-Ni layer, and the coercivity was evaluated. The double-layered films with the same layer thickness (12 μm for Fe-Ni layer and 12 μm for Fe
₂₂
Ni
₇₈
one) showed lower coercivity compared with the single-layered Fe-Ni films. To confirm the effect of the exchange coupling between both layers, we changed the layer thickness for the Fe
₂₂
Ni
₇₈
magnetic phase from 1 to 12 μm, keeping at 24 μm of the total film thickness. The coercivity of the double-layered films was dramatically decreased with increasing the layer thickness of the Fe
₂₂
Ni
₇₈
phase from 1 to 6 μm. This result suggests that the exchange coupling works effectively to reduce the coercivity of the Fe-Ni phase when the Fe
₂₂
Ni
₇₈
layer thickness is >6 μm. Consequently, we increased the saturation magnetization without the increase in the coercivity and concluded that the use of the exchange coupling is one of the attractive methods to prepare soft magnetic materials with good magnetic properties.