Nonlinear Resistance in Nanotubes

Scaling of Resistance and Electron Mean Free Path of Single-Walled Carbon Nanotubes

M.S. Purewal, B.H. Hong, A. Ravi, B. Chandra, J. Hone, and Philip Kim

PRL 98, 186808 (2007)

URL: http://link.aps.org/abstract/PRL/v98/e186808

This group from Columbia University has attached a series of electrodes to individual carbon nanotubes and measured the current-voltage characteristics of carbon nanotubes as a function of temperature and length between electrodes. This allowed them to analyze the scaling behavior of the resistance in single nanotubes.

Using the Landauer-Buttiker model of resitance, the group extracted the mean free path of electrons in the nanotube and studied this as a function of temperature. They find crossover behavior between two types of scaling. Below a critical temperature, the mean free path approaches a constant that differs from one nanotube to the next --- i.e., it depends on the diameter and chiral angle. Above the critical temperature, the authors find universal scaling: the mean free path is inversely proportional to the temperature.

The low temperature behavior is consistent with models based on impurity scattering while the high temperature behavior is consistent with electron-phonon scattering.

At extremely long length scales and low temperatures, the authors find that the resistance no longer scales linearly with the distance between the source and drain. The critical length at which nonlinear behavior starts to dominate is much larger than the electron mean free path, which suggests it is not the result of Anderson localization or a similar type of quantum interference. The phase coherence length is the same order of magnitude as the mean free path, and therefore much shorter than the critical length scale. The authors imply there is no satisfactory theoretical explanation of the observed behavior.

This was the first paper on nanotubes with a recommendation from the editors. It is well-written and reports an interesting result, so the endorsement is well-deserved.