The nature of anomalous conduction of wave packets in disorder-free incommensurate multiwalled carbon nanotubes was explored. The spectrum-averaged diffusion exponent was obtained by calculating the multifractal dimension of the energy spectrum. Depending on the shell chirality, the exponent was found to lie within the range ½ ≤ η < 1. For large unit-cell mismatch between incommensurate shells, η approached the value 1/2 for diffusive motion. The energy-dependent quantum spreading revealed a complex density-of-states-dependent pattern with ballistic, superdiffusive, or diffusive character.

Anomalous Diffusion and Elastic Mean Free Path in Disorder-Free Multiwalled Carbon Nanotubes. Wang, S., Grifoni, M., Roche, S.: Physical Review B, 2006, 74[12], 121407