Thin-Film GMI Elements with High Sensitivity.

Abstract

A very large magneto-impedance (MI) effect was found in CoSiB/Cu/CoSiB and FeCoSiB/Cu/FeCoSiB elements fabricated by the RF magnetron sputtering method. The Cu layer was covered with amorphous magnetic layers and most of the ac current was applied in the Cu layer. An easy axis was added in the transverse direction, perpendicular to the ac current, of the magnetic layers. As a result, when an external magnetic field was applied in the longitudinal direction, very large impedance change ratios were achieved, such as 330%/9 Oe at 10 MHz and 120%/9 Oe at 1 MHz. These ratios are larger by three orders of magnitude than those of a single-layered element.