Magnetic and Structural Characterization of NiFe/Fe30Co70 Bilayers

Magnetostrictive films are required for a wide range of device applications; by increasing the magnetostriction constant and decreasing the anisotropy field, the devices will become more efficient. This paper has studied Fe₃₀Co₇₀ films on different thicknesses of the soft magnetic underlayer Ni₈₁Fe₁₉, to determine how the structural and magnetic properties change. It was found that the anisotropy field of the Fe₃₀Co₇₀ film could be reduced by 50% to 10 kA/m and the magnetostriction constant increased by a factor 4 to 65 ppm when grown on 30 nm Ni₈₁Fe₁₉. This was due to the NiFe underlayer inducing a BCC(110) texture within the Fe₃₀Co₇₀ film and reducing the in-plane stress.