Spin-Selective Transport of Electron in a Quantum Dot under Magnetic Field

We study electronic spin-polarised transport in a system composed of a quantum dot (QD) connected to one normal metal electrode and one ferromagnetic one. The electrical current of each spin component and the spin accumulation on the QD are calculated by using the nonequilibrium Green's function method. We find that in the Coulomb blockade regime, the current spin polarisation can reach 100% under a strong magnetic field. Meanwhile, the spin accumulation on the QD approaches to unit, and thus the dot is occupied by electrons of one certain spin orientation. The system can operate as a spin injector from a normal metal reservoir to a semiconductor material, and may find real usage in solid state quantum information processes.