Geometrical dependence of decoherence by electronic interactions in a GaAs/GaAlAs square network

TL;DR

This study experimentally confirms how the geometry of a GaAs/GaAlAs square network influences electron-electron interaction-induced decoherence, revealing different temperature dependencies for trajectories winding around the rings versus those that do not.

Contribution

It provides the first experimental evidence that decoherence due to electron-electron interactions depends on the geometry of the metallic network.

Findings

Envelope decoherence length scales as T^{-1/3}

Oscillating decoherence length scales as T^{-1/2}

Different length scales govern winding and non-winding trajectories

Abstract

We investigate weak localization in metallic networks etched in a two dimensional electron gas between $25\:$mK and $750\:$mK when electron-electron (e-e) interaction is the dominant phase breaking mechanism. We show that, at the highest temperatures, the contributions arising from trajectories that wind around the rings and trajectories that do not are governed by two different length scales. This is achieved by analyzing separately the envelope and the oscillating part of the magnetoconductance. For $T\gtrsim0.3\:$K we find $\Lphi^\mathrm{env}\propto{T}^{-1/3}$ for the envelope, and $\Lphi^\mathrm{osc}\propto{T}^{-1/2}$ for the oscillations, in agreement with the prediction for a single ring \cite{LudMir04,TexMon05}. This is the first experimental confirmation of the geometry dependence of decoherence due to e-e interaction.