Microstructure and soft magnetic properties of FeSiAl(Ti/Ta)(O)N

The microstructure and magnetic properties of FeSiAl(Ti/Ta)(O)N films prepared by rf magnetron reactive sputtering were studied. The microstructure was controlled by changing the Nz gas flow rate ratio [eta = N-2/(Ar + N-2)] in the sputtering gas. The soft magnetic properties were observed after thermal treatment at around eta of 2% and eta of 20%, where the saturation magnetostrictions and the intrinsic stresses took small values. The film with eta of 20% had a granular structure as mostly observed on nanocrystalline materials. On the other hand, the film prepared with eta of 2% had the structure which consisted of needle shaped grains or dendritic grains. The composition of the granular grains and needle shaped grains were mainly Fe and FeSi, respectively. The film with eta of 2% exhibited B-s of 1.3 T, permeability of 3000-8000 at 1 MHz, respectively, and realized a high corrosion resistance. The soft magnetic properties of the films with needle shaped grains are explained by two-dimensional random anisotropy effect. (C) 1998 American Institute of Physics.