Magnetic properties of Fe-Ta-(b)-N films

The in-plane magnetic anisotropy and thickness dependence of soft magnetic properties for Fe-Ta-N films near the eutectic composition, annealed either in a rotating magnetic field, in a static field, or with no magnetic field, were investigated in detail. The soft magnetic films were prepared by RF reactive sputtering. The films with thicknesses greater than around 2 μm have good soft magnetic properties. For those with thicknesses less than around 1 μm, the soft magnetic properties deteriorate and the domain structure changes with decreasing thickness. The films annealed without magnetic field or in a rotating field have an isotropic high permeability (μ´⩾5000 at 1 MHz) and a low anisotropy field (H_k≃50 A/m), whereas for the films annealed in a static field, uniaxial anisotropy is induced. This anisotropy increases with increasing N concentration. Moreover, B was added to the Fe-Ta-N system, and the relation between the structures and soft magnetic properties of Fe-Ta-B-N films was investigated. By adding B to Fe-Ta-N system, the thermal stability of soft magnetic properties is improved