Magneto-impedance effect of amorphous Fe73.5Cu1Nb3Si13.5B9 ribbons with Ni80Fe20 permalloy film

Abstract

Different thickness of Ni80Fe20 films are deposited on the Fe73.5Cu1Nb3Si13.5B9 amorphous ribbons using RF (radio frequency) magnetron sputtering method. The magnetic properties and magneto impedance effect are measured and compared with as-cast Fe73.5Cu1Nb3Si13.5B9 amorphous ribbons. The results show that the ribbon coated with 260 nm Ni80Fe20 layer achieves a much better performance than others, which produces a GMI (giant magneto-impedance) ratio of 33.0%. It is found that the surface of 260 nm Ni80Fe20 layer is smoother and the particle size is relatively smaller. The hysteresis loops of the ribbons with and without Ni80Fe20 coating layer are almost unchanged. However, the hysteresis loops of the Ni80Fe20 films sputtered onto glass substrate indicate the shift of anisotropy direction from parallel to normal to the surface as the thickness increases. The shifting will influence the magnetic exchange interaction between the amorphous ribbons and the Ni80Fe20 coating layers. The variation of GMI effect can be interpreted by the surface structure and magnetic exchange interaction.