Magnetic field induced delocalization in multi-wall carbon nanotube-polystyrene composite at high fields

Ravi Bhatia (1) , J. Galibert (2) , Reghu Menon (1)

1 IISc Bangalore - Indian Institute of Science [Bangalore]
2 LNCMI-T - Laboratoire national des champs magnétiques intenses - Toulouse

In well dispersed multi-wall carbon nanotube-polystyrene composite of 15 wt%, with room temperature conductivity of similar to 5 S/cm and resistivity ratio [R-2K/R-200K] of similar to 1.4, the temperature dependence of conductivity follows a power-law behavior. The conductivity increases with magnetic field for a wide range of temperature (2-200 K), and power-law fits to conductivity data show that localization length (xi) increases with magnetic field, resulting in a large negative magnetoresistance (MR). At 50T, the negative MR at 8 K is similar to 13% and it shows a maximum at 90K (similar to 25%). This unusually large negative MR indicates that the field is delocalizing the charge carriers even at higher temperatures, apart from the smaller weak localization contribution at T < 20 K. This field-induced delocalization mechanism of MR can provide insight into the intra and inter tube transport. (C) 2013 Elsevier Ltd. All rights reserved.

Mots clés: ELECTRICAL-PROPERTIES; HOPPING CONDUCTION; MAGNETOTRANSPORT; LOCALIZATION

Domaines: Physique [physics]; Matière Condensée [cond-mat]

Ravi Bhatia, J. Galibert, Reghu Menon. Magnetic field induced delocalization in multi-wall carbon nanotube-polystyrene composite at high fields. Carbon, 2014, 69, pp.372-378. ⟨10.1016/j.carbon.2013.12.038⟩. ⟨hal-02146589⟩