Crackling noise and complexity in natural systems
Gianfranco Durin
Istituto Nazionale di Ricerca Metrologica (I.N.Ri.M), Torino, Italy
Is there any relation between a devastating earthquake, a snow avalanche,
some drops of water in a sponge, or a ferromagnet along an hysteresis loop?
Despite huge differences, all these natural systems respond to external
perturbations by a burst of events on a broad range of sizes. This random response is commonly termed as 'crackling noise', and represents a common feature of
many complex systems.
After a general introduction of the main features of this noise, we aim to
present the most recent results in the particular crackling noise produced
in
soft magnetic materials, known as Barkhausen noise. Many of the
theoretical and
experimental results obtained in ferromagnets can in fact be applied with
success to the study of other complex systems. This helps us to understand
complexity within a more general theoretical framework, and focus the role
of
criticality and universality to set the noise properties.