Asymmetric characteristics of magnetoimpedance in amorphous Fe _77.5 Si_7.5 B₁₅ wire

The magnetoimpedance (MI) are measured as functions of measuring frequency, DC-biased current and torsion angle of -50° to + 50° on Fe _77.5Si_7.5B₁₅ amorphous wire. The MI profile for 1 MHz measuring frequency, due to the wall motion in circular direction, shows one symmetric peak for the positive torsion angle, where counterclockwise direction is taken as positive. However, for the negative angle up to 30°, two asymmetric peaks are revealed for decreasing field and one peak for increasing field, and then become one peak for the further angle. The shape of asymmetric MI profile changes sensitively with the direction of DC-biased current for negative torsion. However, there is no change with current for positive torsion.