Enhancement of Sensitivity on Miniaturized Thin-film Magnetoimpedance with Ellipsoidal Element

We tried to control the distribution of the demagnetizing field inside magnetoimpedance elements fabricated using thin-film to gain higher sensitivity. Elements with quasi-ellipsoidal shape were adopted to modify the demagnetizing field distribution, because it is well known that the demagnetizing field is expected to be uniform in an ellipsoid. The larger impedance change and higher sensitivity were obtained in the ellipsoidal elements compared to those of the conventional rectangular elements. The observed results were analyzed by the calculations on the basis of the distribution of the demagnetizing field and the impedance profile without demagnetizing effect. The calculations well explained the experimental results: the improvement of sensitivity and the performance for the ellipsoidal elements is attributed to the uniform distribution of demagnetizing field. The experimental results demonstrate a potential and the calculation results contribute to optimum design, for a miniaturization of magnetoimpedance element in order to keep the higher sensitivity.