Spin accumulation and pure spin current in a three-terminal quantum dot ring with Rashba spin-orbit effect

Based on the Keldysh nonequilibrium Green's function technique, we study the spin accumulation and the pure spin current in a three-terminal quantum ring device, in which a quantum dot (QD) is inserted in one arm of the ring and the Rashba spin-orbit interaction (RSOI) exists in the other. We find that under certain circumstances, the pure spin current in the middle lead and the spin accumulation in the QD emerge simultaneously. The sign and the magnitude of them can be modulated by adjusting the bias voltages, the RSOI-induced phase factor and the magnetic flux penetrating the ring. The origin of the spin accumulation and the pure spin current is interpreted in terms of the spin-dependent total effective coupling strengths between the leads and the QD. (c) 2008 American Institute of Physics.