Probing the transport property of each individual wall within a multiwall carbon nanotube

We report the atomic-scale imaging with concurrent transport measurements of the breakdown$^{ }$of individual multiwall carbon nanotubes inside a transmission electron microscope equipped with a piezo manipulator [1]. We found unexpectedly three distinct breakdown sequences, namely, from the outermost wall inward, from the innermost wall outward, and alternatively between the innermost and the outmost walls. Remarkably, a significant amount of current drop was observed when an innermost wall is broken, proving unambiguously that every wall is conducting. Moreover, the breakdown of each wall in any sequence initiates in the middle of the nanotube, not at the contact, proving that the transport is not ballistic. [1] J. Y. Huang et al., Phys. Rev. Lett. 94, 236802 (2005).