Eur. Phys. J. B (2013) 86: 237
https://doi.org/10.1140/epjb/e2013-30747-6

Regular Article

Perfect spin filtering and conditions for Fano antiresonance and Dicke resonance in a parallel coupled triple quantum-dot array

¹ Department of Physics and Wuhan National High Magnetic field center, Huazhong University of Science and Technology, Wuhan 430074, P.R. China
² China Center of Advanced Science and Technology (CCAST), Beijing 100080, P.R. China

^a e-mail: hhfu@mail.hust.edu.cn

Received: 14 August 2012
Received in final form: 25 January 2013
Published online: 29 May 2013

Abstract

Electronic transport through a parallel coupled triple quantum dot (tQD) array has been studied by means of nonequilibrium Green’s function formalism. By producing an energy difference between the site energy in the upper QDs and down ones, we find that the linear conductance spectrum of this tQD array displays Fano antiresonance and Dicke resonance effects. As the energy difference increases or the tQD chain length increases to a not very large value, the antiresonance valley in the conductance changes to a well-defined insulating band with very steep edges. Meanwhile, the relations of the Fano antiresonance and the well-defined insulating band are explored, and the conditions for the Fano antiresonance and the Dicke resonance are presented. By introducing a Zeeman splitting due to an external magnetic field, the spin-splitting conductance spectrum shows some highly to 100% spin-polarized windows (SPWs). If a gate voltage runs in these SPWs, we can achieve an entirely spin-polarized current, indicating that such a tQD array can be used as a perfect spin filter and a quantum-signal generator. Moreover, the intradot Coulomb repulsion on the electronic transport is also investigated. The results show that the intradot Coulomb repulsion does not affect the device applications for this system mentioned above.