Effect of rotating direction and interval on giant magneto-impedance of sputtered Ni ₈₀Fe ₂₀/Cu composite wires

In this paper, a new method for fabricating Ni ₈₀Fe ₂₀/Cu composite wires is presented. A series of samples were prepared by alternating the rotating direction of the Cu wire during RF magnetron sputtering. In order to keep the overall coating thickness of all the samples constant, the alternating intervals and rotating period of each sample during sputtering were varied. As the rotating period increased, the samples showed different magneto-impedance profiles. Experimental results indicated that there was a critical thickness for single sputtered layer which the MI ratio was significantly enhanced at a relatively low driven current frequency. Qualitative discussion on these phenomena was explained in terms of exchange interaction and electromagnetic interactions.