Carbon nanotube tori under external fields

Abstract

We address here a theoretical study on the role played by external magnetic and electric fields on the electronic properties of toroidal carbon nanotubes. A single-$\ensuremath{\pi}$ band tight-binding calculation is adopted and real-space renormalization techniques are used to obtain electronic energy spectra. Induced gap modulations are found by applying electric and magnetic fields in different spatial configurations. By changing electronic and transport properties of the annular structure with the fields, metal-insulator transitions are allowed for particular tube geometries an field intensities.