Nonequilibrium relaxations and aging effects in a two-dimensional coulomb glass

The relaxations of conductivity have been studied in the glassy regime of a strongly disordered two-dimensional electron system in Si after a temporary change of carrier density during the waiting time t(w). Two types of response have been observed: (a) monotonic, where relaxations exhibit aging, i.e., dependence on history, determined by t(w) and temperature; (b) nonmonotonic, where a memory of the sample history is lost. The conditions that separate the two regimes also have been determined.