Electrical, magneto-transport and localization of charge carriers in nanocomposites based on carbon nanotubes

Here we investigate the electrical transport and magneto-transport properties of a network of singlewalled carbon nanotubes (SWNT) embedded into an insulating polymer matrix in order to build a nanocomposite. We show that the SWNT metallic character is lost in the nanocomposite. Intrinsic localization of the carriers at the bundle size is evidenced from conductivity results. It is confirmed by magnetoresistance measurements which exhibit quantum interference effects in the localized regime. By comparison with isolated SWNT, another difference is found in the role of the Coulomb interactions. Building an ensemble of SWNT allows a partial screening of these interactions as revealed from the ohmic and non ohmic conductivity temperature and field dependencies. (C) 2003 Elsevier Ltd. All rights reserved.