CONDUCTIVITY AND ATOMIC-STRUCTURE OF ISOLATED MULTIWALLED CARBON NANOTUBES

We report associated high-resolution transmission electron microscopy (HRTEM) and transport measurements on a series of isolated multiwalled cart on nanotubes. HRTEM observations, by revealing relevant structur al features of the tubes, shed some light on the variety of observed t ransport behaviors, from semiconducting to quasi-metallic type. Non-Oh mic behavior is observed for certain samples which exhibit ''bamboo-li ke'' structural defects. The resistance of the most conducting sample exhibits a pronounced maximum at 0.6 K and strong positive magnetoresi stance.