Structure and Magnetic Anisotropy of Fe-N Films Prepared by Ion Assisted Vapor Deposition

Changes in the structure and magnetic properties of Fe-N films prepared by ion-assisted vapor deposition were examined, varying the ion current density and substrate temperature. The film structure was characterized by X-ray diffraction techniques and the magnetic anisotropy was evaluated by torque curve measurements. When both the ion current density and the substrate temperature are low, a uniaxial anisotropy is induced by ion bombardment. The origin of the uniaxial anisotropy is not known. With increasing ion current density and substrate temperature, a cubic film texture develops, and an anisotropy with four-fold symmetry appears. As the directions of closest-packed atoms in the film microstructure are coincident with the direction of ion incidence, it is thought that the dependence of the sputtering yield on the grain orientation causes the texture development. The results of experiments using other ion species (Ar, Ne) are also indicated.