Eur. Phys. J. B 67, 71-75 (2009)
https://doi.org/10.1140/epjb/e2009-00003-1

Curvature and external electric field effects on the persistent current in chiral toroidal carbon nanotubes

Department of Physics & Institute for Nanophysics and Rare-earth Luminescence, Xiangtan University, Xiangtan, 411105, Hunan, P.R. China

Corresponding authors: ^a nxu@xtu.edu.cn - ^b jwding@xtu.edu.cn

Received: 24 September 2008
Revised: 9 December 2008
Published online: 9 January 2009

Abstract

Taking into account the intrinsic curvature, we calculate the persistent currents (I_pcs) in chiral toroidal carbon nanotubes (TCNs) by developing the supercell approach. It is shown that in the presence of curvature, the typical current (I_ty) oscillates with the unit cell number (P) and tends to be zero, while it damps exponentially in the absence of curvature. Due to the curvature effects, especially, a paramagnetism-diamagnetism transition is observed in chiral TCNs, depending on the ring diameter and chirality. In addition, the effect of external electric field energy (E_ef) on persistent current is also explored. It is shown that in the presence of electric field, I_ty vary unmonotonously with E_ef. A pronounced peak of I_ty is obtained at high E_ef region. By modulating the value of E_ef, a paramagnetism-diamagnetism or diamagnetism- paramagnetism transition is observed.