Conductance statistics in small insulating GaAs:Si wires at low temperature. II. Experimental study

Abstract

We have observed reproducible conductance fluctuations at low temperature in a small GaAs:Si wire driven across the Anderson transition by the application of a gate voltage. We analyse quantitatively the log-normal conductance statistics in terms of truncated quantum fluctuations. Quantum fluctuations due to small changes of the electron energy (controlled by the gate voltage) cannot develop fully due to identified geometrical fluctuations of the resistor network describing the hopping through the sample. The evolution of the fluctuations versus electron energy and magnetic field shows that the fluctuations are non-ergodic, except in the critical insulating region of the Anderson transition, where the localization length is larger than the distance between Si impurities. The mean magnetoconductance is in good accordance with simulations based on the Forward-Directed-Paths analysis, i.e. it saturates to $\ln (\sigma (H>1)/\sigma (0))\simeq 1,$ as $\sigma (0)$ decreases over orders of magnitude in the strongly localized regime.

Email contact: [email protected]

Cited by in corpus (7)

• Anomalous Conductance Distribution in Quasi-One Dimension: Possible Violation of One-Parameter Scaling Hypothesis
• Distribution Function Analysis of Mesoscopic Hopping Conductance Fluctuations
• Notes on Decoherence at Absolute Zero
• Gate-modulated thermopower of disordered nanowires: II. Variable-range hopping regime
• Coexistence of anomalous field effect and mesoscopic conductance fluctuations in granular aluminium
• Numerical studies of variable-range hopping in one-dimensional systems
• Parametric statistics of the scattering matrix: From metallic to insulating quasi-unidimensional disordered systems