A. Vaknin

Impairing the Memory of an Electron-Glass by IR Excitation

We study the influence of various excitations on the anomalous field effect observed in insulating indium-oxide films. In conductance G versus gate-voltage Vg measurements one observes a characteristic cusp around the Vg at which the system has equilibrated. In the absence of any disturbance this cusp may persist for a long time after a new gate voltage was imposed on the sample and hence reflects a memory of the previous equilibrium state. This memory is believed to be related to the correlations between electrons. Here we show that exciting the conduction electrons by exposing the sample to IR light degrades this memory. We argue that any excitation that randomizes the system destroys the correlations and therefore impairs the memory.We study the influence of various excitations on the anomalous field effect observed in insulating indium-oxide films. In conductance G versus gate-voltage Vg measurements one observes a characteristic cusp around the Vg at which the system has equilibrated. In the absence of any disturbance this cusp may persist for a long time after a new gate voltage was imposed on the sample and hence reflects a memory of the previous equilibrium state. This memory is believed to be related to the correlations between electrons. Here we show that exciting the conduction electrons by exposing the sample to IR light degrades this memory. We argue that any excitation that randomizes the system destroys the correlations and therefore impairs the memory.

Transport in the electron-glass under energy pumping

The conductance G of In 2 O 3-x films in the hopping regime has been measured as function of time for a fixed temperature and at various electric fields F. When F is switched at t = 0 from F 1 to F 2 > F 1 the conductance increases reflecting the non-Ohmic nature of field assisted hopping. However, G(F 2 , t > 0) is observed to be non-stationary - it increases with time in a sluggish manner. After F 2 is re-adjusted to F 1 , the conductance slowly approaches its equilibrium value. The latter is presumably the slow relaxation process previously reported to occur in electron glasses excited far from equilibrium. The magnitudes of these non-ergodic effects depend on F and vanish for F < F * , the field below which G is Ohmic. The temporal evolution of G(F 2 ) is ascribed to the slow increase of the electron energy due to the action of F.