Martinek J, Sindel M, Borda L, Barnaś J, König J, Schön G, von Delft J
Institut für Theoretische Festkörperphysik, Universität Karlsruhe, 76128 Karlsruhe, Germany.
Phys Rev Lett. 2003 Dec 12;91(24):247202. doi: 10.1103/PhysRevLett.91.247202. Epub 2003 Dec 10.
The Kondo effect in quantum dots (QDs)-artificial magnetic impurities-attached to ferromagnetic leads is studied with the numerical renormalization group method. It is shown that the QD level is spin split due to the presence of ferromagnetic electrodes, leading to a suppression of the Kondo effect. We find that the Kondo effect can be restored by compensating this splitting with a magnetic field. Although the resulting Kondo resonance then has an unusual spin asymmetry with a reduced Kondo temperature, the ground state is still a locally screened state, describable by Fermi liquid theory and a generalized Friedel sum rule, and transport at zero temperature is spin independent.
利用数值重整化群方法研究了附着在铁磁引线中的量子点（QD）——人工磁杂质中的近藤效应。结果表明，由于铁磁电极的存在，量子点能级发生自旋分裂，导致近藤效应受到抑制。我们发现，通过施加磁场补偿这种分裂可以恢复近藤效应。尽管由此产生的近藤共振具有不寻常的自旋不对称性且近藤温度降低，但基态仍然是一个局部屏蔽态，可用费米液体理论和广义弗里德尔和规则来描述，并且零温度下的输运与自旋无关。
