Soft magnetic properties of [FeTaN/N-rich FeTaN]n multilayer films

We investigated the soft magnetic properties of FeTaN multilayers which consist of Fe78.8Ta8.5N12.7 films with a periodic insertion of thin (∼100 Å) N-rich FeTaN layers. The FeTaN multilayer leads to an enhancement of magnetic anisotropy compared to the single layer. This enhancement can be explained in terms of increased tensile stresses in the multilayer after heat treatments. The degree of anisotropy is found to depend on the stacking number of [FeTaN/N-rich FeTaN]n layers. The stress-induced anisotropy ultimately improves the high-frequency characteristics through restricting ferromagnetic resonance. The optimum multilayer exhibits the following good soft magnetic properties: permeability of 2500, coercivity of 0.1 Oe, magnetic anisotropy field of 6 Oe, and stable frequency response up to 300 MHz.