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arXiv 0808.3496cond-mat.mes-hallcond-mat.str-el
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三角形量子点中近藤效应的栅压依赖性

Gate-voltage dependence of Kondo effect in a triangular quantum dot

T. Numata, Y. Nisikawa, A. Oguri, A. C. Hewson

摘要:

利用数值重整化群研究了三角形三重量子点与两个相互作用的导线的电导。研究发现,系统表现出多种近藤效应,这取决于三角形的填充。在半填充时出现SU(4)近藤效应,在栅压依赖性中出现由于相位变化引起的急剧电导下降。此外,当平均四个电子占据三个位置时,沿着三角形诱导出由长冈机制引起的局部S=1的矩。三角形的熵和自旋磁化率的温度依赖性表明,该时刻通过在不同温度下的两个单独的阶段被传导电子屏蔽。在SU(4)或S=1的近藤效应发生时,二端和四端电导在栅压下有明显的差别。

英文摘要:

We study the conductance through a triangular triple quantum dot, which are connected to two noninteracting leads, using the numerical renormalization group (NRG). It is found that the system shows a variety of Kondo effects depending on the filling of the triangle. The SU(4) Kondo effect occurs at half-filling, and a sharp conductance dip due to a phase lapse appears in the gate-voltage dependence. Furthermore, when four electrons occupy the three sites on average, a local S=1 moment, which is caused by the Nagaoka mechanism, is induced along the triangle. The temperature dependence of the entropy and spin susceptibility of the triangle shows that this moment is screened by the conduction electrons via two separate stages at different temperatures. The two-terminal and four-terminal conductances show a clear difference at the gate voltages, where the SU(4) or the S=1 Kondo effects occurring.

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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