Effect of seed and interface layers on the magnetic properties of laminated Fe-Al-N films

We have prepared several sets of multilayers [S/Fe-Al-N]_N by radio-frequency-diode sputtering, using NiFe and Al₂O₃ as spacer S. We investigated magnetic and structural properties as a function of spacer and Fe-Al-N thickness. By transmission electron microscopy and X-ray diffraction investigations, we could show that the doping of the Fe with Al as well as the nitriding effect of the Ar/N₂ sputtering atmosphere results in a nanocrystalline structure, leading to coercivities below 2.5 Oe in all films. Optimized lamination improves the properties to give excellent soft magnetic behavior with easy axis coercivity <0.5 Oe and closed hard-axis hysteresis loops with H_k in the range of a few oersteds. The observed degradation of this soft magnetism when the lamination is changed cannot be explained solely by changes of the structural properties.