Nitrided FeB amorphous thin films for magneto mechanical systems

The structural, magnetic and magnetoelastic properties of Fe–B–N amorphous films, sputtered from a Fe80B20 target, in a mixture of argon and nitrogen gas, are studied for different nitrogen partial pressures. Nitrogen incorporates into the film preserving the amorphous structure, and modifying magnetic properties. The amount of nitrogen that incorporates into the amorphous structure is found to scale linearly with the nitrogen partial pressure during film growth. The structure, magnetization, field evolution, magnetic anisotropy and magnetostrictive behaviour are determined for films with different nitrogen content. An ∼20% increase of both the saturation magnetization and the magnetostriction constant values is found for moderate (∼8%) nitrogen content when compared to those for pure Fe80B20 amorphous films. These improved properties, together with the still low coercivity of the amorphous films offer great potential for their use in magnetostrictive micro and nano magneto mechanical actuator devices.