Magnetoimpedance effect in nanocrystalline Fe73.5Cu1Nb3Si13.5B9 single-layer and bilayer ribbons

The magnetoimpedance (MI) response in field-annealed soft magnetic Fe73.5Cu1Nb3Si13.5B9 nanocrystalline ribbons has been studied for samples with single-layer and bilayer geometry. We have found that bilayer ribbons reveal higher magnetoimpedance values at low frequencies (typically between 2 and 5 MHz), while single-layer ribbons exhibit more pronounced MI effect at intermediate frequencies (above 10 MHz). The correlations between the MI effect and ribbon thickness are discussed in terms of skin effect. The highest sensitivity (η) 65%/Oe was achieved for the samples annealed in magnetic field applied transverse to the ribbon length. The observed findings are of practical importance to develop high-sensitivity magnetic sensors.