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arXiv 1301.4512cond-mat.mes-hall
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近藤量子点与铁磁引线耦合中的光诱导效应

Asymmetry-induced effects in Kondo quantum dots coupled to ferromagnetic leads

K. P. Wojcik, I. Weymann, J. Barnas

摘要:

我们研究了近藤机制下强耦合到铁磁引线的单能级量子点的自旋分辨输运,重点研究了接触和材料不对称相关的效应。利用数值重整化群方法,分析了相关谱函数、线性电导和隧道磁电阻随系统非对称性参数的变化关系。在器件的平行磁结构中,由于交换场的存在,近藤效应通常被抑制,而与系统的不对称性无关。另一方面,在反平行结构中,如果系统是对称的,则可以产生近藤效应。我们发现,即使是相对较弱的不对称性可能会导致抑制的近藤共振的反平行配置,从而引起非平凡的行为的隧道磁电阻。此外,我们还利用二阶微扰理论导出了系统两种磁位形下交换场的一般公式。

英文摘要:

We study the spin-resolved transport through single-level quantum dots strongly coupled to ferromagnetic leads in the Kondo regime, with a focus on contact and material asymmetry-related effects. By using the numerical renormalization group method, we analyze the dependence of relevant spectral functions, linear conductance and tunnel magnetoresistance on the system asymmetry parameters. In the parallel magnetic configuration of the device the Kondo effect is generally suppressed due to the presence of exchange field, irrespective of system's asymmetry. In the antiparallel configuration, on the other hand, the Kondo effect can develop if the system is symmetric. We show that even relatively weak asymmetry may lead to the suppression of the Kondo resonance in the antiparallel configuration and thus give rise to nontrivial behavior of the tunnel magnetoresistance. In addition, by using the second-order perturbation theory we derive general formulas for the exchange field in both magnetic configurations of the system.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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