The Effect of Varying Current on the Impedance Phase Characteristics of CoFeSiB Amorphous Ribbon

The impedance magnitude characteristics of the giant magnetoimpedance (GMI) sensors have been extensively researched since the magnetoimpedance (MI) effect was discovered 20 years ago. However, unlike earlier impedance amplitude studies, the current study shows that the characteristic shift of the GMI impedance phase is more sensitive to the change in the magnetic field. CoFeSiB exhibits excellent GMI effect and soft magnetic characteristics. The impedance phase characteristics of an amorphous ribbon of CoFeSiB are examined in this work in relation to fluctuations in the excitation current. The impedance phase characteristics are significantly influenced by the magnitude and frequency of the ac excitation current as well as the degree to which the dc current overlapped the ac current. When the dc bias current is zero, the sensitivity in the weak field is roughly 0.79%/Oe. The sensitivity can reach up to 3.97%/Oe in the same field when the dc bias current is set to 20 mA. The GMI phase sensitivity change rate has seen a further increase of almost 402.5%. It indicates that the appropriate excitation current amplitude and frequency can excite the maximum impedance phase change.