Magnetoimpedance effect of FINEMET ribbons coated with Fe20Ni80 permalloy film

Abstract To study the electromagnetic interaction mechanism between different soft magnetic materials, a series of specimen with different thickness Ni 80 Fe 20 film were deposited onto nanocrystalline Fe 73.5 Cu 1 Nb 3 Si 13.5 B 9 ribbons by magnetron sputtering. X-ray diffraction revealed a slightly structural variation of the ribbons as thickness of the Ni 80 Fe 20 film ranging from 0 to 520 nm. The surface roughness of Ni 80 Fe 20 layer was investigated by Atomic Force Microscopy, showing no significant variation with different thickness of Ni 80 Fe 20 layer. The hysteresis loops and the coercivity value indicated the shift of anisotropy direction from parallel to normal to the surface as the Ni 80 Fe 20 thickness increased, thus influencing the magnetic exchange interaction. Compared to the bare Fe 73.5 Cu 1 Nb 3 Si 13.5 B 9 ribbons, coating of Ni 80 Fe 20 films significantly enhanced the giant magnetoimpedance response of the ribbons. The 24% improved GMI ratio was achieved in the ribbon with 260 nm thick Ni 80 Fe 20 film.