Quantum spin and charge pumping through double quantum dots with ferromagnetic leads |
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Authors: | Hui Pan,Ziyu ChenSufen Zhao,Rong Lü |
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Affiliation: | a Department of Physics, Beijing University of Aeronautics and Astronautics, Beijing 100191, China b Key Laboratory of Micro-Nano Measurement-Manipulation and Physics (Ministry of Education), Beihang University, Beijing 100191, China c Department of Physics, Tsinghua University, Beijing 100084, China |
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Abstract: | The pumping of electrons through double quantum dots (DQDs) attached to ferromagnetic leads have been theoretically investigated by using the nonequilibrium Green?s function method. It is found that an oscillating electric field applied to the quantum dot may give rise to the pumped charge and spin currents. In the case that both leads are ferromagnet, a pure spin current can be generated in the antiparallel magnetization configuration, where no net charge current exists. The possibility of manipulating the pumped spin current is explored by tuning the dot level and the ac field. By making use of various tunings, the magnitude and direction of the pumped spin current can be well controlled. For the case that only one lead is ferromagnetic, both of the charge and spin currents can be pumped and flow in opposite directions on the average. The control of the magnitude and direction of the pumped charge and spin currents is also discussed by means of the magnetic flux threading through the DQD ring. |
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Keywords: | Quantum pump Spin and charge current Double quantum dots |
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