Despite decades of intensive studies, some aspects of charge transport through carbon nanotubes (CNTs) remain poorly understood. Here, we explore the transport properties of field-effect devices based on metallic CNTs, where the density of states is supposed to be constant and a field effect is not anticipated. The observed current-voltage characteristics are qualitatively different from these expectations. The conductance of our devices shows significant modulation as a function of gate voltage. However, the minimal conductance does not show a temperature dependence, with the on/off ratio being constant in a wide temperature range. Still, when an axial magnetic field is applied, an Arrhenius temperature dependence of the minimal conductance is observed. The observed effects are naturally explained by the CNT's band-structure modifications under the metallic electrodes at the CNT edges. Our results provide experimental proof of the predicted structural deformations of CNTs in side-contacted devices.

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• Density of states
• Electrical conductivity
• Electrical properties
• Quantum transport