Non-Gaussian conductance noise in disordered electronic systems

The results of conductance-noise experiments on disordered films of crystalline indium oxide in their glassy phase are discussed. The power-spectrum of the noise has the usual 1/f form, and when measured under small bias, the noise is Gaussian even in samples as small as 2 μm. However at larger voltages V used in the conductance measurements the noise may acquire non-Gaussian features with a non-trivial dependence on V. Theoretical model relating this behavior to a non-linear effect inherent to electronic transport in a hopping system is presented. It is concluded that the non-Gaussian features can be observed whenever the system is glassy.