Studies of low-frequency resistance noise demonstrate that glassy freezingoccurs in a two-dimensional electron system in silicon in the vicinity of themetal-insulator transition (MIT). The width of the metallic glass phase, whichseparates the 2D metal and the (glassy) insulator, depends strongly ondisorder, becoming extremely small in high-mobility (low-disorder) samples. Theglass transition is manifested by a sudden and dramatic slowing down of theelectron dynamics, and by a very abrupt change to the sort of statisticscharacteristic of complicated multistate systems. In particular, the behaviorof the second spectrum, an important fourth-order noise statistic, indicatesthe presence of long-range correlations between fluctuators in the glassyphase, consistent with the hierarchical picture of glassy dynamics.
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