Materials World Network: Novel Physical Phenomena in Unusual Mesoscopic Superconductors

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。这个材料世界网络（MWN）团队由来自中国、哥伦比亚、日本、瑞士和美国的五名实验学家和两名理论家组成，旨在研究不寻常的、大部分未开发的介观超导体。特别是它1）研究超小介观超导体，其特征在于单、双或多连接的样品几何形状以及破坏性区域; 2）研究介观的、常规的s波超导体和/或与非常规的、手征p波超导体接壤的正常金属; 3）研究p波超导体-铁磁金属-超导体（S/F/S）约瑟夫森结，以理解交换和库珀对相互作用之间的相互作用;四是研究与教育活动相结合。这项工作旨在通过改变样品拓扑结构和同时缩小样品尺寸来揭示新的物理现象，利用最近发现的非常规介观超导系统，或者冒险制造和测量奇异的p波S/F/S约瑟夫森结，理论上已经预测了戏剧性的现象。通过这些研究，我们期望获得新的见解，样品的拓扑结构依赖的介观超导和非常规超导，包括约瑟夫森耦合通过铁磁a势垒。要探索的介观超导系统的不寻常性质以及它们以前在很大程度上未被探索的事实似乎确保了新发现的充足机会。此外，该MWN团队拥有包括超纯单晶生长在内的广泛技术专长先进的电子束光刻技术和聚焦离子束纳米加工技术，精密的结构和光谱特性（Z对比透射电子显微镜和低温扫描隧道显微镜和光谱），高度专业化的器件制造（SFS约瑟夫森结）和低温测量（稀释冰箱温度）。在理论方面，我们的团队包括计算建模，现象学和微观理论的专家。 这项研究为使用介观超导体用于未来的技术应用奠定了基础，也为研究和教育的有意义的整合提供了有效的工具，旨在为我们的研究生和本科生提供一个国际化的学习和研究环境。该计划有助于吸引更多的女性和少数民族学生的人才来从事物理科学事业。除了通过学生交流和我们的国际合作者的访问，为我们的学生提供在多机构，多文化环境中的研究经验。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). This Materials World Network (MWN) team consists of five experimentalists and two theorists from China, Colombia, Japan, Switzerland, and the US to investigate unusual, mostly unexplored mesoscopic superconductors. In particular it 1) studies ultrasmall mesoscopic superconductors that feature a singly, doubly, or multiply connected sample geometry as well as a destructive regime; 2) investigates mesoscopic, conventional s-wave superconductor, and/or a normal metal bordered by an unconventional, chiral p-wave superconductor; 3) explores p-wave superconductor-ferromagnetic metal-superconductor (S/F/S) Josephson junctions to understand the interplay between exchange and Cooper pairing interactions; and finally, 4) pursues integrated research and education activities. This work seeks to uncover novel physical phenomena by varying the sample topology and shrinking the sample size simultaneously, making use of recently discovered unconventional mesoscopic superconducting systems, or venturing into the fabrication and measurement of exotic p-wave S/F/S Josephson junctions for which dramatic phenomena have been predicted theoretically. Through these studies we expect to obtain new insights into sample-topology dependent mesoscopic superconductivity and unconventional superconductivity including Josephson coupling through a ferromagnetic a barrier. The unusual nature of the mesoscopic superconducting systems to be explored and the fact that they have largely been unexplored previously appear to ensure ample opportunities for new discoveries. In addition, this MWN team possesses an unusually wide range of technical expertise including ultrapure single crystal growth (by floating zone method), advanced e-beam lithography and focused ion beam nanofabrication, sophisticated structural and spectroscopic characterization (Z-contrasted transmission electron microscopy and low-temperature scanning tunneling microscopy and spectroscopy), highly specialized device fabrication (SFS Josephson junctions), and low-temperature measurements (dilution-refrigerator temperatures). On the theoretical side, our team includes specialists on computational modeling, phenomenology, and microscopic theories. This research lays a foundation for using mesoscopic superconductors for future technological applications and also serves as an effective vehicle for meaningful integration of research and education aiming at providing our graduate and undergraduate students an international environment for learning and research. This program helps attract more talents from the vast pool of woman and minority students to pursue a career in physical sciences. In addition to providing our students research experience in a multi institution, multi-culture environment through student exchange and the visits of our international collaborators.