Soft magnetic properties of bcc Fe-Zr-B sputtered films with nanoscale grain size

Abstract

A nanoscale bcc film with a grain size of 10 to 20 nm was found to be prepared by annealing sputtered Fe-Zr-B amorphous films with solute contents of 4 to 9 at% Zr and 1 to 6 at% B for 3.6 ks in the temperature range of 823 to 923 K. The bcc Fe89.8Zr7.7B2.7 film obtained by annealing at 923 K exhibits a high magnetization (Bxn) of 1.64 T at an applied field of 800 kA/m and a high permeability (μ,) of 3200 at 1 MHz. It is notable that the BMN and μ, values are comparable to the highest values for various kinds of soft magnetic films reported so far. The reason for the appearance for the good soft magnetic properties is presumably due to the decrease in apparent magnetic anisotropy by the formation of the nanocrystalline bcc structure and the reduction of magnetostriction caused by the dissolution of Zr into the bcc phase.