Magnetic properties of nanocrystalline Fe86.7Zr3.3B4Ag6 thin film

Abstract The changes of magnetic properties with annealing temperature were studied in the amorphous Fe 86.7 Zr 3.3 B 4 Ag 6 thin film. The thin films were deposited by a DC magnetron sputtering method, annealed at 300–700°C for 1 h in vacuum under a field of 1.5 kOe parallel to the film plane, and then furnace-cooled. As a result, it has been found that the Ag addition to Fe–Zr–B amorphous thin films resulted in the decrease of crystallization temperature to 400°C due to promoted crystallization ability. Also, it gave rise to formation of fine BCC α-Fe crystalline precipitates with a grain size smaller than 10 nm in the amorphous matrix near 400°C, and led to prominent enhancement in the magnetic properties of the Fe 86.7 Zr 3.3 B 4 Ag 6 thin films. Significantly, excellent magnetic properties such as a saturation magnetization of 1.7 T, a coercive force of 1 Oe and a permeability of 7800 at 50 MHz were obtained in the amorphous Fe 86.7 Zr 3.3 B 4 Ag 6 thin film containing 7.2 nm-size BCC α-Fe, which was annealed at 400°C. Also, core loss of 1.4 W cm −3 ( B m =0.1 T) at 1 MHz in the thin film was obtained, and it is a much lower value than had been obtained in any existing soft magnetic materials. Such excellent properties are inferred to originate from the uniform dispersion of nano-size BCC α-Fe in the amorphous matrix.