The Barkhausen effect: a true introduction

So you know, the 'actors' of the Barkhausen effect are the Domain Walls (seen here) jumping in their motion across a sample.

But, there is a particular moment in a hysteresis loop when they jump...and this is around the coercive field:

Animation of the Barkhausen signal (1Hz)

This animation has been taken for a Co-base amorphous alloy at 1 Hz (see below the effect of frequency)

You can see the same picture in detail (do not loose it: it's very nice!)

Clearly, this noise does not show avalanches, or Barkhausen jumps, but a fluctuating signal around some average value

Decreasing the frequency, we can see well defined Barkhausen jumps!

Look at the animated gifs (about 30 kB each), and note the different time scales

As long as the frequency tends to zero, the more separated in space and time, showing power law distributions and critical exponents, a common feature of complex disordered systems.

Look a fine example of the noise around the coercive field and the power law distributions:

Home, my activity, the Barkhausen effect, papers & publications, my family, my hobbies, links