Magnetoconductance of carbon nanotubes

Abstract

As a result of the interaction between the spin and the magnetic field (B), special step structures are predicted to exist in the ballistic magnetoconductance of carbon nanotubes. The electronic structure of a carbon nanotube drastically changes from a metal (semiconductor) to a semiconductor (metal) during the variation of the magnetic flux. When the spin-B interaction is neglected, the Fermi level only touches the conductance and valence bands of a metallic nanotube. This paramagnetic interaction could make the subbands cross and intersect with the Fermi level within a certain magnetic-flux range; the ballistic magnetoconductance thus exhibits step structures. Such special structures are expected to be observable at low temperature (1 K) and bias voltage (0.1 mV). Moreover there exists another effect, the doping effect, which could lead to step structures even without the spin-B interaction.