ABSTRACT
The electron-glass dynamics of Anderson-localized GeSbTe films is dramatically slowed down following a brief infrared illumination that increases the system carrier concentration (and thus its conductance). These results demonstrate that the dynamics exhibited by electron glasses is more sensitive to carrier concentration than to disorder. In turn, this seems to imply that many-body effects such as the orthogonality catastrophe must play a role in the sluggish dynamics observed in the intrinsic electron glasses.
ABSTRACT
We report on measurements of absorption from applied ac fields in Anderson-localized indium-oxide films. The absorption shows a roll-off at a frequency that is much smaller than the electron-electron scattering rate measured at the same temperature in diffusive samples of this material. These results are interpreted as evidence for discreteness of the energy spectrum.
ABSTRACT
We study the time-dependent conductance of electron glasses excited by electromagnetic radiation at microwave and infrared frequencies. In either case, the conductance G is enhanced during exposure, but its time dependence after the radiation is turned off is qualitatively different depending on the frequency. For comparison, results of excitation produced by a gate voltage and temperature changes are also shown. The glassy nature of the system allows us to demonstrate that the microwave-enhanced conductance is not due to heating. These findings are discussed in terms of an energy E_{c} that characterizes the equilibrium charge distribution of the electron glass.
ABSTRACT
It is experimentally shown that, depending on the carrier concentration of the system n, the dynamics of electron glasses either slows down with increasing temperature or it is independent of it. This also correlates with the dependence of a typical relaxation time (or "viscosity") on n. These linked features are argued to be consistent with a model for dissipative tunneling. The slow relaxation of the electron glass may emerge then as a manifestation of friction in a many-body quantum system. Our considerations may also explain why strongly localized granular metals are likely to show electron-glass effects while semiconductors are not.
ABSTRACT
A new protocol for an aging experiment is studied in the electron-glass phase of indium-oxide films. In this protocol, the sample is exposed to a non-Ohmic electric field F for a waiting time t(w) during which the system attempts to reach a steady state (rather than relax towards equilibrium). The relaxation of the excess conductance Delta G after Ohmic conditions are restored exhibits simple aging as long as F is not too large.
ABSTRACT
Aging, commonly observed in glasses, is a manifestation of breakdown of time-translational invariance. Here we demonstrate experimentally aging effects in the electronic system of an Anderson insulator. The aging phenomenon in the electron glass appears to be much less sensitive to temperature than in other systems. The differences in the behavior of the electron glass and a spin glass system are discussed in terms of some microscopic differences between the two systems.
