Kondo screening and Fano resonance in hybrid Superconductor-Quantum dot devices

报告人

李林 博士 南方科技大学物理系

报告时间

时间：2015年12月25日上午10点30（星期五）

报告地点

太阳成集团虎溪校区理科楼0638太阳集团LE523

报告摘要

We investigate theoretically the Andreev transport through a quantum dot strongly coupled with a normal metal/ferromagnet and a superconductor (N/F-QD-S), in which the interplay between the Kondo resonance and the Andreev bound states (ABSs) has not been clearly clarified yet. Here we show that the interference between the Kondo resonance and the ABSs modifies seriously the lineshape of the Kondo resonance, which manifests as a Fano resonance. The ferromagnetic lead with spin-polarization induces an effective field, which leads to splitting both of the Kondo resonance and the ABSs. The spin-polarization together with the magnetic field applied provides an alternative way to tune the lineshape of the Kondo resonances, which is dependent of the relative positions of the Kondo resonance and the ABSs. These results indicate that the interplay between the Kondo resonance and the ABSs can significantly affect the Andreev transport, which could be tested by experiments.

For a normal-quantum dot-superconductor (N-QD-S) device, the microscopic mechanism of Kondo screening is still under the debates. It is found that the spin-induced Yu-Shiba-Rusinov (YSR) bound state possesses effective local moment. The YSR bound state evolves into the Andreev bound states (ABSs) in the presence of normal lead, which are significantly broadened by increasing the coupling. The Kondo resonance observed in Andreev transport can be recognized as the screening of ABSs by the normal lead. Different from the Kondo effect of magnetic impurity in metal, the spin-flipping tunneling through the ABSs level must be associated with the Andreev reflection process.

报告人介绍

李林 博士，南方科技大学助理研究员，2012年获兰州大学理论物理博士，香港大学博士后，获深圳市高层次人才“孔雀计划”，主要从事强关联电子系统，量子输运理论，拓扑绝缘与拓扑超导体等凝聚态理论方面的研究。目前主持国家和广东省省级自然科学基金各1项，以第一作者在Phys. Rev. B, Phys. Rev. E,New. J. Physics，APL等国际权威期刊上发表论文多篇，New. J. Physics文章被评选为2013年该杂志年度亮点工作，研究成果得到国际同行的关注和认可，被国际性期刊引用共60余次数。

联系人

王锐 rcwang@cqu.edu.cn

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