Giant Barkhausen effects with second order instability (abstract)

Idealized giant Barkhausen (BG) jumps in amorphous wires result in a simple rectangular hysteresis loop. There is a range of domain wall depinning fields so that if the depinning field for magnetization in the central section of the wire is high enough, magnetization reversal takes place by domains becoming depinned at the end of the wire. This leads to the rectangular hysteresis loop characteristic of GB. We have observed a different kind of Barkhausen effect in Fe‐B‐Si amorphous wires under a variety of conditions. The magnetization starts linearly with field, then displays a roughly quadratic field dependence, saturating at lower fields than that given by the low field linear extrapolation. In the quadratic region the plot of log(Hs−H) vs log(Ms−M), where Hs is the apparent saturation magnetization taking place at field Hs, is linear with a slope of 1/2. This is typical of simple second order instability processes. Thus, instead of a first order giant Barkhausen jump we have observed a second order Bar...