CoFe-based amorphous alloy with high relaxation frequency

Amorphous Co43Fe20B31.5Ta5.5 ribbons prepared by melt-spinning technique, showed a relaxation frequency fx of 3MHz, higher than any other known amorphous alloy. Additional complex permeability measurements reflected the reversible bulging of domain walls as the active magnetization mechanism below fx. The magnetoimpedance (MI) effect was also detected for this alloy, with a maximum variation of 1.6% at 5MHz. A positive saturation magnetostriction of 0.085×10−6 was estimated from tension-stress–MI measurements.