Magnetic Field Dependence of the Energy Gap in Nanotubes

Abstract

The dependence of the energy gap in the band structure of a carbon nanotube on the flux of an external uniform magnetic field is studied in the framework of the zero‐range potential method. Taking into account a renormalization procedure for the coupling constant of the zero‐range potential, we obtain an estimate for the maximal gap between the conductivity band and the valence one; this estimate is closer to experimental data when compared to the value given by the tight‐binding approximation. It is shown numerically that decreasing the diameter of nanotubes breaks down the flux periodicity of the gap structure.

Keywords:

• Nanotubes
• magnetic field
• energy gap, zero‐range potential

Acknowledgment

The paper was partially supported by Grants of DFG–RAS, INTAS and Russian Federal Education Agency (Research Project 1.02.00).