Concentration dependence of microstructure and soft magnetic properties in the FeSi-ZrO₂ granular films

Magnetic films composed of FeSi and ZrO₂ with the oxide concentration in the range of 21-35wt% were prepared by using electron beam-physical vapor deposition method. From X-ray diffraction patterns, it was found that the magnetic film consisted of α-Fe and ZrO₂. Energy dispersion X-ray spectroscopy analysis showed that Si composition was around 1.5wt%. The transmission electron microscopy images showed that a granular structure was obtained for the films containing high ZrO₂ content, with the Fe(Si) grain size of around 10nm. While for the film containing low ZrO₂ content, the structure is more like a random aggregate of the Fe(Si) and ZrO₂ phases. High saturation magnetization of 11.02-16.8kG and comparatively large electrical resistivity of 392.5-75.1μΩcm were obtained for the films. The coercivity of the film containing 21wt% ZrO ₂ was much smaller than that of the film with 35wt% ZrO₂ concentration. It is assumed that the existence of ZrO₂ could reduce the grain size of the magnetic granules while weakening the magnetic interaction among the magnetic granules.