Eddy-current anomaly in Fe-based nanocrystalline wires

Abstract The circular permeability, μ = μ ′− jμ ″, of two Fe-based nanocrystalline wires obtained by furnace annealing (S1) and by current annealing (S2) were determined from the measurements of the impedance, Z = R + jωL , as a function of frequency ( f =0.1–100 kHz) and DC bias field ( H =0–89 kA/m). So the H -dependent low- f eddy-current anomaly factor, η ( H ), has been investigated. The experimental results indicate that the sample S2 by current annealing has a larger η =4 than the sample S1 by furnace annealing with η =2.8 at H =0. With increasing H , the η ( H ) of two samples decreases initially until about H =450 A/m, and then increases very quickly. These results have been analyzed by the helical magnetization model considering the contribution of domain wall displacements (DWD) and domain magnetization rotation (DMR).