Circular electron propagation in carbon nanotubes?

[gildomar]

Can carbon nanotubes support electron propagation perpendicular to the axis? That is, can there be circular current flow on the tube's perimeter, not just the linear flow parallel to the axis? Because I reading that it's generally considered a 1-dimensional conductor.

 

[TeethWhitener]

Can carbon nanotubes support electron propagation perpendicular to the axis? That is, can there be circular current flow on the tube's perimeter, not just the linear flow parallel to the axis? Because I reading that it's generally considered a 1-dimensional conductor.

Yes, electrons can propagate around the circumference of the nanotube. They're called 1-dimensional because most of their practical applications employ their conductive properties along the long axis of the wire. But the structure of the tube about its circumference (specifically its twist, or helicity) strongly affects its overall electronic structure: namely, whether the tube is metallic or semiconducting.

 

[gildomar]

Yes, electrons can propagate around the circumference of the nanotube. They're called 1-dimensional because most of their practical applications employ their conductive properties along the long axis of the wire. But the structure of the tube about its circumference (specifically its twist, or helicity) strongly affects its overall electronic structure: namely, whether the tube is metallic or semiconducting.

Ok, cool. Because I thought that it only supporting conduction along the axis sounded a little strange.

 

[TeethWhitener]

I don't know if I'd really call it "conduction" around the circumference, as that tends to be more of a term applied to macroscopic length scales. But if you localise an electron wavepacket at one area along the circumference, it will spread out around the circumference. I suppose strictly speaking, if you laid a CNT on a gold surface with its axis parallel to the plane and came in from above with, e.g., an STM tip, you'd see conduction across it. I don't know if anyone's done that experiment though. A more important point, though, is that the helicity of the CNT imposes a boundary condition on the propagation of an electron, through its effect on the band structure of the CNT along the axis.