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Spin-dependent Transport of a Quantum Dot Coupled with Ferromagnetic Electrodes

A research team (Prof. Zhang Ping, Prof. Wang Yupeng, Prof. Xue Qikum, and Prof. Xie Xincheng) at the International Center of Quantum Structures, Institute of Physics, Chinese Academy of Sciences (CAS), has recently made some important progress in the field of quantum-computing and spintronics. The team theoretically investigated the influence of electron correlation interaction and spin-flip on spin tunneling transport in a quantum dot (QD). A model, in which a QD with two spin-degenerate local levels is coupled with external ferromagnetic electrodes through tunneling, was constructed. Their numerical calculations show that the Kondo resonance and the correlation-induced spin splitting of the dot levels can be systematically controlled by internal magnetization in the electrodes. Two spin-resolved resonant peaks exist in the linear conductance spectrum when the magnetization directions of the two magnetic electrodes are parallel. This novel spin-valve effect is induced by the combination of strong correlation and external magnetic coupling. The influence of spin-relaxation has destructive effect on spin-splitting and spin-valve effect, while it creates new resonant peaks in the spectrum of local density of states. This work was published in Physical Review Letters 89,286803(2002) on November 31st, 2002.The project was supported by CAS, NSFC and MOST.
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