Effect of dc current on magneto-impedance in CoSiB twisted wires

The input impedance of a coaxial waveguide with a twisted CoSiB amorphous w ire experiencing the application of a de magnetic field and a de current ha s been measured for frequencies up to 500 MHz. Under the effect of the de c urrent, the magneto-impedance (MI) behavior exhibits a considerable change. At frequencies of 50-100 MHz, a sharp narrow impedance peak seen for a zer o current becomes broader, as the current is increased, and shifts towards higher fields. For higher frequencies, the MI curves are generally very bro ad. The application of the current results in a pronounced asymmetry and hi gher sensitivity. The asymmetrical MI characteristics are caused by a combi ned effect of a spiral anisotropy induced by wire twist and a circular magn etic field created by the de current. Such impedance behavior is important for linear sensing application. (C) 2000 Elsevier Science S.A. All rights r eserved.