https://doi.org/10.1140/epjb/e2009-00195-2
Controlled π-junctions in a T-shaped double quantum dot system
1
Department of Physics, Beijing University of
Aeronautics and Astronautics, Beijing, 100083, P.R. China
2
Department of Electrical and Computer Engineering, Colorado
State University, Fort Collins, CO, 80523, USA
Corresponding author: a hpan@buaa.edu.cn
Received:
16
January
2009
Revised:
6
April
2009
Published online:
3
June
2009
The π-junction transition of a T-shaped double quantum dot system is investigated theoretically by using the nonequilibrium Green's function method. It is found that the π-junction transition can occur with increasing the spin-flip strength. Furthermore, the π-junction in the system can be controlled by tuning the system parameters, such as the two quantum dot energy levels and the interdot coupling. These controlled π-junction transitions are interpreted in the picture of current-carrying density of states. When the main contributions to supercurrent is changed between the positive discrete spectrum and the negative continuous spectrum, the π-junction transitions can happen.
PACS: 74.45.+c – Proximity effects; Andreev effect; SN and SNS junctions / 73.23.-b – Electronic transport in mesoscopic systems / 73.63.Kv – Quantum dots
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2009
