Electric field induced suppression of universal conductance fluctuations and dephasing in disordered systems

TL;DR

This study demonstrates that small electric fields can suppress universal conductance fluctuations in disordered systems by inducing electron wavefunction dephasing, revealing a new method to measure electron coherence.

Contribution

It introduces electric field induced dephasing as a novel mechanism to control and measure conductance fluctuations in disordered conductors.

Findings

UCF can be suppressed by small electric fields.

Dephasing rate depends on temperature and electric field.

UCF can serve as a sensitive electron interferometer.

Abstract

We report a novel phenomenon that the universal conductance fluctuations (UCF) can be suppressed by a small electric field E. The experiment has been carried out on single crystals of Si doped heavily with P and B beyond the critical composition of insulator to metal transition. The phenomenon is identified as a consequence of electric field induced dephasing of the electron wavefunction. Over the range of measurements, the observed dephasing rate (\tau_\phi^{-1}) varied as \tau_\phi^{-1} = aT + bE^q with q \approx 1.3 and for E >> E^*, a cross-over field, \tau_\phi^{-1} \sim E^q, independent of T. This experiment also establishes that the UCF can be utilized as a sensitive electron "interferometer" to measure dephasing rate.