Contact and non-contact magnetoimpedance in amorphous and nanocrystalline Fe73.5Si13.5B8CuV3Al ribbons

The giant magnetoimpedance (GMI) effect in amorphous and nanocrystalline Fe73.5Si13.5B8CuV3Al ribbons has been studied as a function of a dc magnetic field, by contact and non-contact methods. In the contact method, an MI of 19% was obtained in the nanocrystalline ribbon while it is of the order of 104 in the non-contact method. The huge sensitivity of the non-contact method is promising with regard to the increase of the sensitivity of the MI sensors. Field dependence of MI has shown double peak behavior in contact method and single peak profile in non-contact method. The domains were found to lie normal to the plane of the ribbon, through MFM studies. All the experimental results were discussed using the Polivanov model.