通知公告

(7.17)学术报告:Destructive regime, superconducting fluctuations, Little-Parks-de Gennes effect in doubly connected mesoscopic superconductors

来源: 时间:2015-07-15

报告人:Ying Liu (刘荧)教授 Pennsylvania State University &Shanghai Jiao Tong University

邀请人:田明亮 研究员

时间:2015.7.17,10:00(周五)

地点:强磁场5楼报告厅

摘要

Sample topology plays an important role in determining the properties of mesoscopic superconductors.  The Little-Parks effect, the quantum oscillations of the superconducting transition temperature with the applied flux, was observed long ago in doubly connected superconducting cylinders. Its limiting behavior, the loss of the global superconducting phase coherence near the half-flux quanta found in ultrasmall doubly connected rings or cylinders with a diameter smaller than the superconducting coherence length, referred to originally by de Gennes as the destructive regime, was found more recently. Here the superconductivity is destroyed because of the doubly connected sample topology that leads to a competition between the kinetic and the condensation energies. Moreover, de Gennes predicted that the global phase coherence in such doubly connected samples could be tuned by the addition of a side branch, referred to as the Little-Parks-de Gennes effect, which was confirmed experimentally recently.  I will present measurements on ultrathin doubly connected cylinders and ultrasmall loops of Al that led to the observation of the destructive regime and the Little-Parks-de Gennes effect and the exploration of depairing tuned superconducting quantum fluctuations near the onset of the destructive regime.

简历

刘荧教授分别从北京大学物理系获学士学位,中科院物理研究所硕士学位,美国明尼苏达大学博士学位。现任美国宾州州立大学物理系教授、上海交通大学“千人计划”鸿文讲席教授。他的主要研究方向为凝聚态实验和量子材料物理,在反常超导,量子相变、纳米物理、强关联体系等方面的研究上取得了世界公认的成果,发表 论文80 余篇,其中Nature 1 篇,Science 4 篇,PNAS 1 篇,Phys.Rev.Lett. 9 篇。曾获得美国自然科学基金委的事业奖(NSF Career Award)和中国自然科学基金委的杰青奖(B类)和中国教育部长江教授(B类)。刘荧教授是美国物理学会会士。

欢迎感兴趣的老师和同学参加!

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