Induced Giant Magnetoimpedance Effect by Current Annealing in Ultra Thin Co-Based Amorphous Ribbons

We have studied the magnetoimpedance (MI) response of near-zero magnetostriction (Co
$_{0.95}$
Fe
$_{0.05}$
)
$_{75}$
Si
$_{10}$
B
$_{15}$
(Co-based) amorphous ribbons (0.50 mm wide, 32
$\mu$
m thick), thermally treated by current annealing, for different dc current of intensity varying from 440–680 mA during 5 min, was investigated in the frequency range of 10 MHz–1 GHz. It was not observed MI effect in the as-quenched ribbon, while the current annealed ribbons display large MI depending on the current annealing intensity in a similar way to that of the inhomogeneous induced magnetic anisotropy developed by this peculiar thermal treatment.