Bias-controllable intrinsic spin polarization in a quantum dot: Proposed scheme based on spin-orbit interaction

We propose a novel scheme to efficiently polarize and manipulate the electron spin in a quantum dot. This scheme is based on the spin-orbit interaction and it possesses following advantages: (1) The direction and the strength of the spin polarization is well controllable and manipulatable by simply varying the bias or the gate voltage. (2) The spin polarization is quite large even with a weak spin-orbit interaction. (3) Both electron-electron interaction and multienergy levels do not weaken but strengthen the spin accumulation. (4) The spin-flip time can reach to the order of 10(-11) s. (5) The device is free of a magnetic field or a ferromagnetic material. (6) It can be easily realized with present technology.