  Systems that produce crackling noises such as Barkhausen pulses are
statistically similar and can be compared with one another. In this project,
the Barkhausen noise of three ferroelectric lead zirconate titanate (PZT)
samples were demonstrated to be compatible with avalanche statistics. The peaks
of the slew-rate (time derivative of current $dI/dt$) squared, defined as
jerks, were statistically analysed and shown to obey power-laws. The critical
exponents obtained for three PZT samples (B, F and S) were 1.73, 1.64 and 1.61,
respectively, with a standard deviation of 0.04. This power-law behaviour is in
excellent agreement with recent theoretical predictions of 1.65 in avalanche
theory. If these critical exponents do resemble energy exponents, they were
above the energy exponent 1.33 derived from mean-field theory. Based on the
power-law distribution of the jerks, we demonstrate that domain switching
display self-organised criticality and that Barkhausen jumps measured as
electrical noise follows avalanche theory.
