Spin-polarized current and shot noise in the presence of spin flip in a quantum dot via nonequilibrium Green's functions
| Autor: | Souza, F. M., Jauho, A. P., Egues, J. C. |
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| Rok vydání: | 2008 |
| Předmět: | |
| Zdroj: | Phys. Rev. B 78, 155303 (2008) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevB.78.155303 |
| Popis: | Using non-equilibrium Green functions we calculate the spin-polarized current and shot noise in a ferromagnet--quantum-dot--ferromagnet (FM-QD-FM) system. Both parallel (P) and antiparallel (AP) magnetic configurations are considered. Coulomb interaction and coherent spin-flip (similar to a transverse magnetic field) are taken into account within the dot. We find that the interplay between Coulomb interaction and spin accumulation in the dot can result in a bias-dependent current polarization $\wp$. In particular, $\wp$ can be suppressed in the P alignment and enhanced in the AP case depending on the bias voltage. The coherent spin-flip can also result in a switch of the current polarization from the emitter to the collector lead. Interestingly, for a particular set of parameters it is possible to have a polarized current in the collector and an unpolarized current in the emitter lead. We also found a suppression of the Fano factor to values well below 0.5. Comment: Published version. 13 pages, 7 figures |
| Databáze: | arXiv |
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