Low-Frequency Noise as a Tool to Study Disordered Materials

The use of noise to determine the properties of defects in crystalline matter and the types of dynamical coherence in various glassy structures is described. Some introduction is given to traditional and new analysis tools, especially ones using non-Gaussian statistics. Many examples are provided in glasses, metals with defects, spin glasses, charge-density waves, disordered domain structures, magnetic vortices in superconductors, and related areas. The focus is on quasi-equilibrium effects, but driven noise, e.g. the Barkhausen effect, is also discussed. The examples range from testing theories of the spin-glass state to in situ testing of the stress in steel cables.