Anderson localization regime in carbon nanotubes: size dependent properties

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Abstract
The influence of disorder and defects is of fundamental relevance in the performance of nanotube-based devices. It is then crucial to understand the properties of (as-grown or in situ created) defects in order to conquer their detrimental effects, but also to tune nanotube properties in a desired direction. We show experimentally and theoretically the formation, in different single-walled carbon nanotubes, of a strong Anderson localization regime in which the electrical resistance increases exponentially with the length of the nanotube. This implies that, in these systems, the coherence length can be much longer than the localization length. We also show how the localization length depends strongly on the tube diameter and it increases as the tube diameter is enlarged. Furthermore, we analyse in detail the role of temperature on electron localization, demonstrating that this strong localization regime survives to nearly room temperature: the net effect of the temperature is to wash out the strong fluctuations that appear at zero temperature. (Some figures in this article are in colour only in the electronic version)