Onset of glassy dynamics in a two-dimensional electron system in silicon

The fluctuations of conductivity sigma with time have been studied in a two-dimensional electron system in low-mobility Si inversion layers. The noise power spectrum is approximately 1/f(alpha) with alpha exhibiting a sharp jump at an electron density n(s) = n(g). A huge increase in the relative variance of sigma is observed as n(s) is reduced below n(g), reflecting a dramatic slowing down of the electron dynamics. This is attributed to the freezing of the electron glass. The data strongly suggest that glassy dynamics persists in the metallic phase.