Magnetoimpedance of FeNi-based asymmetric sensitive elements

• Giant magnetoimpedance effect.
• Non-symmetric multilayers sructure.
• Biosensing.

[Ti/FeNi]5/Ti/Cu/Ti/[FeNi/Ti]x (x=0–5) multilayers were prepared by sputtering. Their magnetic properties and magnetoimpedance were studied focusing on future technological applications. Both (ΔZ/Z)max and (ΔR/R)max values showed a tendency to decrease with a decrease of the number of magnetic layers of the top multilayer. Such a parameter as an even or odd number of layers is important for the MI value. In the field interval of technological interest all [Ti/FeNi]5/Ti/Cu/Ti/[FeNi/Ti]x structures show similar sensitivities of about 70%/Oe for ΔR/R ratios but the lower the number of magnetic layers in the top multilayer, the higher the operating frequency.