Control of saturation magnetization, anisotropy, and damping due to Ni implantation in thin Ni81Fe19 layers

The layer magnetization, the saturation magnetization as well as the magnetic anisotropy, and damping behavior of 20nm thick Ni81Fe19 films have been modified by 30keV Ni ion implantation with fluences up to 1×1016Ni∕cm2 (≈5at.%). With increasing ion fluence a magnetic dead layer of increasing thickness is formed which leads to a reduction of the total magnetization. In addition, the saturation magnetization of the residual ferromagnetic film decreases due to, both, a shift in stoichiometry and radiation damage. Accordingly a reduction of the magnetic anisotropy and a strong enhancement of the magnetic damping parameter are observed. Moreover, ion implantation in an applied magnetic field allows the setting of the uniaxial anisotropy direction irrespective of its original orientation. Static and dynamic magnetic properties of Ni81Fe19 films can be tailored over a wide range after film deposition.