Spin-dependent transport and spin polarization in coupled quantum wells

We theoretically investigate the electron transport and spin polarization of two coupled quantum wells with Dresselhaus spin-orbit interaction. In analogy with the optical dual-channel directional coupler, the resonant tunneling effect is treated by the coupled-mode equations. We demonstrate that spin-up and -down electrons can be completely separated from each other for the system with an appropriate system geometry and a controllable barrier. Our result provides a new approach to construct spin-switching devices without containing any magnetic materials or applying a magnetic field. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.2981204]

973 Program 2006CB604908 2006CB921607 National Natural Science Foundation of China 60625402 The work was supported by the 973 Program (Grant Nos. 2006CB604908 and 2006CB921607), and the National Natural Science Foundation of China (Grant No. 60625402).