Investigation of Driving Power Dependence on Magnetoimpedance Properties of Thin-Film Elements With Uniaxial Anisotropy

We investigated the dependence of driving ac current on the giant magnetoimpedance (GMI) properties of rectangular elements fabricated using thin films with uniaxial anisotropy. Two types of GMI sensor elements were fabricated. One had the typical GMI configuration, with the easy axis parallel to the width of the sensor, and the other had an inclined easy axis. The impedance changes and its change ratio deteriorated with increasing ac current amplitude in the case of the typical type of the GMI element of narrower width. The observed discontinuous impedance jump was suppressed with increasing ac current amplitude for the GMI elements having an inclined easy axis. These behaviors are explained mainly by partial magnetization saturation due to a large excitation field inside the elements. We also discuss a research direction aimed at gaining higher sensitivity in typical GMI elements and the utilization of the discontinuous jump.