The power spectrum of the barkhausen noise of grain-oriented three-percent silicon iron

The Barkhausen effect in specimens of 3-percent silicon iron has been investigated by measuring the Barkhausen noise. The cross power spectrum of the noise voltages, picked up by two coils at different points of one specimen, has also been analyzed ; it yields information about the correlation of the Barkhausen discontinuities in time and space. Because of this correlation, Barkhausen jumps occur in groups, thus causing the normal power spectrum to rise remarkably at low frequencies. Comparing the experimental results with a formula developed by Mazzetti and Montalenti, one gets quantitative data about the groups. We have found that the mean number
\bar{\rho}
of pulses per group and the mean time interval τ between subsequent pulses in a group vary with the irreversible susceptibility like
\rho \sim \chi_{irr}^{2}, \tau \sim \chi_{irr}^{-1}
, no matter how
\chi_{irr}
is changed.