We ascribe the excess noise in metals to random fluctuations with thermally activated characteristic times. From the known temperature dependence of the magnitude of the noise in Ag we infer a narrow distribution of activation energies that peaks in the vicinity of 1 eV. Frequency power laws close to $f^{-1\mathrm{}}$ are deduced and the small variations with temperature are consistent with observations. The predicted spectrum, like the observed one, has an apparent power-law nature throughout the frequency region accessible to experiment.

• Received 21 May 1979

DOI:https://doi.org/10.1103/PhysRevLett.43.646