Response of disordered matter to electromagnetic fields.

We have studied a variety of different disordered materials, including molecular and ionic liquids, supercooled liquids, glasses, ionic conductors, and doped semiconductors, in ac electromagnetic fields over an exceptional broad dynamic range, including the rarely investigated GHz to THz region. All classes of disordered matter exhibit an astonishingly similar response: In addition to Jonscher's time-honored "universal dielectric response," a superlinear power-law increase of the frequency-dependent conductivity shows up bridging the gap between the classical dielectric and the infrared region. Thus the universal dielectric behavior of disordered matter extends up to much higher frequencies than thought until now.