Nano-crystallization and magnetic properties in the highly resistive Fe-Si-Zr-O films prepared by EB-PVD

Fe-Si-Zr-O magnetic thin films were prepared by using electron beam-physical vapor deposition (EB-PVD) method. Structure analysis and microstructure observations revealed that the as-deposited samples were composed of two phases of α-Fe(Si) and ZrO2, with grain sizes in the range of 20-200 nm. After annealing at 473-673 K for 1 h, an ultrafine structure was observed, in particular, when the annealing temperature was 473 K, the grain size was reduced to the order of around 10 nm. It is inferred that the deposited film prepared by EB-PVD went through recrystallization process during annealing, resulting in the uniform nano-structure. A minimum coercivity was achieved after annealing at 473 K. The saturation magnetization was 50.2 emu g-1, remaining unchanged after annealing. Electrical resistivity was obtained to be 1212 μΩ cm-1 for the as-deposited film, and reached the maximum value of 2279 μΩ cm-1 after annealing at 573 K. The result can be explained by the increase of grain boundary due to the formation of ultrafine structure