Giant magnetoimpedance and permeability in nanocrystalline Fe–Nb–B ribbons

In the present work, the giant magnetoimpedance of Fe83Nb6B11 annealed ribbons was investigated. The maximum magnetoimpedance ΔZ/Z0 under longitudinal field H = 7162 A/m can reach −51.44% at an optimum annealing temperature of about 650 °C, where both the permeability and the change of permeability under transverse field show large values. The negative-magnetoreactance decreases with increasing frequency, accompanying the decrease of change ratio of permeability. In contrast, with an increase of frequency the negative-magnetoresistance undergoes a maximum, and then drops. The enhancement of the magnetoresistance at high frequency may be ascribed to the skin effect.