Discussion Topic Posted for the
NANOTUBE-99 Workshop:
Why are nanotubes not superconducting?
Contact person:
tomanek@msu.edu
This appears to be a true mystery in view of the following facts:
- Nanotubes, same as fullerenes, are characterized by the same type of
sp2 bonding as graphite.
- Graphite, when intercalated, becomes superconducting (albeit at very low
tempeartures). Solid C60, when intercalated, is superconducting
well above 30 K. Electron-phonon coupling is responsible for superconductivity
in these two systems.
- The vibrational spectrum of nanotubes in ropes contains the same
high-frequency modes that cause superconductivity in solid C60.
- Same as in graphite, intercalants have been observed to shift the Fermi
level towards the Van-Hove singularities, causing a significant increase in the
density of states and in the observed conductivity. In solid C60
this increase/onset of conductivity has been accompanied by superconducting
behavior.
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