High frequency characteristics of as-sputtered Co-Ni-Fe-N soft magnetic thin films

Abstract

Co-Ni-Fe-N soft magnetic thin films with excellent high frequency characteristics were fabricated by a N2 reactive rf magnetron sputtering method. The nitrogen partial pressure (PN2) was varied in the range of 0 ∼ 10%. As PN2 increases in this range, the saturation magnetization (Bs) linearly decreases from 19.8 kG to 14 kG and the electrical resistivity (ρ) increased from 27 μΩ cm to 155 μΩ cm. The coercivity (Hc) exhibits the minimum value at 4% PN2. The magnetic anisotropy field (Hk) are in the range of 20 ∼ 40 Oe. High frequency characteristics of (Co22.2Ni27.6Fe50.2)100-x Nx films are excellent in the range of 3 ∼ 5% PN2. Especially, the effective permeability of the film fabricated at 4% PN2 is about 800, which is maintained up to 600 MHz. This film exhibits Bs of 17.5 kG, Hc of 1.4 Oe, ρ of 98 μΩ cm, and Hk of about 25 Oe. The corrosion resistance of (Co22.2Ni27.6 Fe50.2)100-xNx is improved with the increase of N concentration.