Fabrication of FM/NM/FM Hetero-Structure Multilayers and Investigation on Structural and Magnetic Properties: Application in GMI Magnetic Sensors

Magnetic thin films of Fe/Cu/Fe and Fe/Cu/Ni multilayers on glass substrates were deposited by thermal evaporation route. The structure and morphology of multilayers were studied by X-ray diffraction (XRD) and atomic force microscopy (AFM). Amorphous formation of the Fe and Ni in multilayer structures and the maximum surface roughness of about 6.11 nm for the Fe/Cu/Fe and 4.8 nm for the Fe/Cu/Ni thin films were observed. Also, magnetization behaviors in perpendicular and parallel fields to the surface were investigated. The behavior of the magnetization indicates a low 5-mT coercive field, the easy in-plane magnetization, and the formation of soft ferromagnetic structure. The giant magneto-impedance response (GMI) to the applied longitudinal magnetic field at 5-MHz frequency was obtained 70% for three-layer Fe/Cu/Fe. Also, the measurements for the Fe/Cu/Ni film show a peak in the external field of about H-ext = 14 Oe and the GMI response of about 95% at 5-MHz frequency. This work provides a preliminary investigation into the high performance of multilayer-based GMI devices for sensor applications.