Eur. Phys. J. B 51, 425-433 (2006)
https://doi.org/10.1140/epjb/e2006-00245-3

Charge and spin currents tunnelling through a toroidal carbon nanotube side-coupled with a quantum dot

¹ CCAST (World Laboratory), P.O. Box 8730, Beijing, 100080, P.R. China
² Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong, P.R. China
³ Department of Physics, Beijing Institute of Technology, Beijing, 100081, P.R. China

Corresponding author: ^a zhaohonk@yahoo.com

Received: 25 March 2006
Published online: 21 June 2006

Abstract

We have investigated the mesoscopic transport through the system with a quantum dot (QD) side-coupled to a toroidal carbon nanotube (TCN) in the presence of spin-flip effect. The coupled QD contributes to the mesoscopic transport significantly through adjusting the gate voltage and Zeeman field applied to the QD. The compound TCN-QD microstructure is related to the separate subsystems, the applied external magnetic fields, as well as the combination of subsystems. The spin current component I_z^s is independent on time, while the spin current components I_x^s and I_y^s evolve with time sinusoidally. The rotating magnetic field induces novel levels due to the spin splitting and photon absorption procedures. The suppression and enhancement of resonant peaks, and semiconductor-metal phase transition are observed by studying the differential conductance through tuning the source-drain bias and photon energy. The magnetic flux induces Aharonov-Bohm oscillation, and it controls the tunnelling behavior due to adjusting the flux. The Fano type of multi-resonant behaviors are displayed in the conductance structures by adjusting the gate voltage V_g and the Zeeman field applied to the QD.