Magnetic Properties of Fe-M-O (M=Zr, Hf) Films with High Resistivity

The magnetic properties of Fe-M-O (M=Zr, Hf≫ films with high electrical resistivity, prepared by the rf magnetron sputtering technique in an Ar+O
₂
atmosphere, were investigated. In the as-deposited state, low coercivities (H
_c
) in the range 30 to 100 A/m were obtained for Fe-Hf-O, and 160 to 240 A/m for Fe-Zr-O, in the composition range characterized by an O/M ratio of between 3 and 4. After annealing under optimum conditions in an external field of 160 kA/m, the results obtained for Fe
_54.9
Hf
₁₁
O
_34.1
and Fe
_65.3
Zr
8.9O_25.8 included a saturation magnetization (B_s) of 1.2 T, an H_c of 64 A/m, and a μ at 100 MHz of 1600 for the former, and a B_s of 1.3 T, H_c of 73 A/m and μ at 100 MHz of 1000 for the latter. Further, the electrical resistivities of the films were much higher than those of known metallic soft magnetic films.