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.