Characterization of Amorphous GMI Thin-Film Meander Trilayers

This paper presents the magnetic properties of CoFeB trilayer thin films in relation to the high-frequency impedance responses. Fifty- and 100-nm-thin amorphous layers with a central 100- and 200-nm-thin Cu layer, respectively, were sputtered onto a thermally oxidized Si wafer. 300-mum-long meanders of 3-20-mum width were structured using a standard mask with various meanders, which were connected in series and were then formed by plasma etching. Magnetization curves, parallel to the easy axis, and hard axis of uniaxial anisotropy, were measured by the magnetooptical Kerr effect exhibiting anisotropy fields of around 2 kA/m and low coercivity in the hard-axis direction, depending on the film thickness. The magnetoimpedance (MI) effect was measured manually from 10 MHz to 1 GHz by means of a network analyzer using the reflected wave through the sample. The maximum effect occurred for both samples at 850 MHz