Weak Localization and Dimensional Crossover in Carbon Nanotube Systems

TL;DR

This study explores how magnetic and electric fields influence electron behavior in carbon nanotubes, revealing weak localization effects and a dimensional crossover from 2D to 3D conductance around 85K.

Contribution

It provides experimental evidence of weak localization and dimensional crossover in carbon nanotube systems, linking conductance behavior to temperature and field effects.

Findings

Weak localization effects observed in magnetoresistance data.

A 2D-3D crossover in conductance occurs near 85K.

Electric field influences electron coherence length.

Abstract

We investigate the effects of magnetic and electric fields on electron wavefunction interactions in single walled carbon nanotube bundles. The magnetoresistance measurements performed at 4.2K and the dependence of the data upon the electric field, obtained by varying the bias current through the samples, reveal good agreement with weak localization theory. Recording current-voltage characteristics at different temperatures we find an ohmic non-ohmic transition which disappears above 85K. Conductance vs temperature measurements are also well explained in the framework of weak localization theory by the predicted temperature dependence of the electric field-conditioned characteristic length. This length results equal to the average bundles diameter just at T{\backcong}85K, indicating that the observed conductance transition is due to a 2D-3D crossover.