Materials World Network: Novel Physical Phenomena in Unusual Mesoscopic Superconductors

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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.