Effects of DC Bias Current on Behavior and Sensitivity of Thin-Film Magnetoimpedance Element

We investigated the behaviors and sensitivity of thin-film magnetoimpedance elements having an easy axis angle of 0°-45° when applying dc bias current directly to the elements. All elements show symmetric impedance profiles with respect to the impedance axis without dc bias current, while their profiles become asymmetric with dc bias current. This appearance of the asymmetric property on the impedance profiles indicates that the shape of cross section of the element has asymmetric configuration. On the other hand, when the easy axis angle is relatively small, the sensitivity for field detection is enhanced with a small dc bias level, while a stronger bias level is required for the element with a larger easy axis angle. The obtained results show a potential to optimize the sensor properties by dc bias current with small intensity in case that design properties are not obtained in the fabrication process.