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arXiv 1306.3657cond-mat.str-el
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微波场驱动单电子晶体管近藤电导的非单调场依赖性

Non-monotonic field dependence of Kondo conductance in a single-electron transistor driven by microwave field

Zhan Cao, Chen Cheng, Fu-Zhou Chen, Hong-Gang Luo

摘要:

在单电子晶体管(SET)中施加的磁场和微波之间的相互作用对近藤效应有着深刻的影响,正如最近的实验所表明的那样[B.海明威,S.赫伯特,M. Melloch和A. Kogan,arXiv:1304.0037(2013)]。在一定的微波频率下,近藤微分电导表现出非单调的磁场依赖性,并在一定的磁场下出现一个非常尖锐的峰值。此外,微波频率被发现比相应的塞曼能量大约一个数量级。这两个特征在当前的理论中是不被理解的。在这里,我们提出了一个现象学的机制来解释这些观察。当在SET中同时施加磁场和微波时,如果频率与(重整化)塞曼能量匹配,则假定微波能够在SET中诱导自旋翻转,这导致两个结果。一个是点能级下移,另一个是塞曼能量的重整化。这一图像不仅可以定性地解释实验中的主要发现,而且可以进一步激发非平衡器件中近藤效应动态响应的相关实验研究。

英文摘要:

The interplay between magnetic field and microwave applied in a single-electron transistor(SET) has a profound influence on the Kondo effect, as shown in a recent experiment[B. Hemingway, S. Herbert, M. Melloch and A. Kogan, arXiv:1304.0037(2013)]. For a given microwave frequency, the Kondo differential conductance shows a non-monotonic magnetic field dependence, and a very sharp peak is observed for certain field applied. Additionally, the microwave frequency is found to be larger of about one order than the corresponding Zeeman energy. These two features are not understood in the current theory. Here we propose a phenomenological mechanism to explain these observations. When both magnetic field and microwave are applied in the SET, if the frequency matches the (renormalized) Zeeman energy, it is assumed that the microwave is able to induce spin-flip in the SET, which leads to two consequences. One is the dot level shifts down and the other is the renormalization of the Zeeman energy. This picture can not only explain qualitatively the main findings in the experiment but also further stimulate the related experimental study of the dynamic response of the Kondo effect in out-of-equilibrium devices.

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