Magnetoimpedance effect of FINEMET ribbons coated with Fe20Ni80 permalloy film

•The exist of electric/magnetic material around will affect magnetic properties.•GMI effect is a useful tool to study magnetic materials.•Exchange interaction exists between the FINEMT ribbon and peralloy film.•The exchange interaction may be varied by the film thickness.•The results was successfully discussed using Herzer models.

To study the electromagnetic interaction mechanism between different soft magnetic materials, a series of specimen with different thickness Ni80Fe20 film were deposited onto nanocrystalline Fe73.5Cu1Nb3Si13.5B9 ribbons by magnetron sputtering. X-ray diffraction revealed a slightly structural variation of the ribbons as thickness of the Ni80Fe20 film ranging from 0 to 520 nm. The surface roughness of Ni80Fe20 layer was investigated by Atomic Force Microscopy, showing no significant variation with different thickness of Ni80Fe20 layer. The hysteresis loops and the coercivity value indicated the shift of anisotropy direction from parallel to normal to the surface as the Ni80Fe20 thickness increased, thus influencing the magnetic exchange interaction. Compared to the bare Fe73.5Cu1Nb3Si13.5B9 ribbons, coating of Ni80Fe20 films significantly enhanced the giant magnetoimpedance response of the ribbons. The 24% improved GMI ratio was achieved in the ribbon with 260 nm thick Ni80Fe20 film.