It is shown that high-frequency current fluctuations induced by the application of a steady electric field to a thin metallic film provide, in certain cases, a way to determine an inelastic-scattering time in a regime where it is otherwise hardly accessible because the usual transport coefficients and equilibrium fluctuations are mainly determined by elastic scattering. The physical meaning of previous calculations on related subjects is also elucidated and extensions of the equilibrium Langevin formalism to nonequilibrium steady states are discussed.

• Received 9 November 1981

DOI:https://doi.org/10.1103/PhysRevB.25.7562