The in‐plane magnetic anisotropy of RF‐sputtered FeNiN thin films

FeNiN thin films were synthesized on Si(100) substrates at room temperature by RF magnetron sputtering. The nitrogen concentration dependence of their phase structure and magnetic properties was systematically investigated. With increasing nitrogen partial pressure (P ), the FeNiN thin films successively showed a α‐Fe phase at P ≤ 5.0%, then a pure ε‐Fe3N phase at P = 25.0%, and then a ζ‐(Fe,Ni)2N phase at P = 25.0%, but there was no γ′‐(Fe,Ni)4N phase in the whole P range. These films with various phases presented different magnetic properties, which can be ascribed to the strong effects of nitrogen content. The optimum soft magnetic properties with Ms of ∼1721 emu/cm3 and HC of <4 Oe were obtained at P = 3.0% at room temperature. In particular, we experimentally found that the nitrogen atoms play a key role in controlling the in‐plane magnetic anisotropy, and the evolution of the in‐plane anisotropy derives from the combined effects of internal stress, shape anisotropy, and induced anisotropy. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)