Onset of Glassy Dynamics in a Two-Dimensional Electron System in Silicon

Abstract

The time-dependent fluctuations of conductivity σhave been studied in a two-dimensional electron system in low-mobility, small-size Si inversion layers. The noise power spectrum is ~1/f^α with αexhibiting a sharp jump at a certain electron density n_s=n_g. An enormous increase in the relative variance of σis 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.

minor changes; to appear in Phys. Rev. Letters