2007 Volume 48 Issue 3 Pages 460-464
In this work the sample length dependence of giant magnetoimpedance for Fe73.5Cu1Nb3Si13.5B9 nanocrystalline ribbons was investigated. The longitudinal magnetoimpedance ΔZ⁄Z0 for Fe73.5Cu1Nb3Si13.5B9 nanocrystalline ribbons decreases with the decreasing of sample length L due to the demagnetization effects. The demagnetization field lowers the permeability, especially for the very shorter sample. The magnetoimpedance ΔZ⁄Z0 experiences a peak under a field Hp due to the existence of transverse anisotropy. Different from the saturation behavior of Hp at high frequencies for longer sample with L=40 mm, there is a maximum phenomenon of peak field HP at about 700∼900 kHz for shorter sample with L=13 mm. With increasing ac frequency, the peak-magnetoimpedance (ΔZ⁄Z0)p also experiences a maximum value for both longer and shorter samples. The maximum peak-magnetoimpedance [(ΔZ⁄Z0)p]max shifts to lower frequency with reduction of sample length.