摘要

Work on small superconductors has been at the forefront of superconductivity research. Traditionally two categories of small superconductors have been studied. The first category of small superconductors, known as mesoscopic superconductors described by Ginzburg-Landau theory, features a sample size on the order of a micron, sufficiently small to allow only few vortices in the sample. The second category of small superconductors includes samples that are so small – with a size on the order of a nanometer - Cooper pairs can barely form because of the quantum-size effect. Recently, the study of small superconductors has been expanded to superconducting samples with an intermediate size, which in addition feature a varied sample topology or an unconventional pairing symmetry. Novel physical phenomena have been observed, which appears to suggest physics beyond Ginzburg-Landau or quantum-size effects. In this talk I will present our experimental results on ultrasmall singly and doubly connected s-wave superconductors and islands of conventional s-wave superconductors bordered by an unconventional, chiral p-wave superconductor. I will also discuss briefly future directions of small superconductor research.

报告人简介

Dr. Ying Liu is a professor of physics at Pennsylvania State University and a Visiting Jiangxi Professor at Shanghai Jiaotong University. He received a B. S. degree from Peking University, Beijing, a M. S. degree at Institute of Physics, Chinese Academy of Sciences, Beijing, and a Ph. D. degree from University of Minnesota, all in physics. He joined the faculty of Department of Physics, Pennsylvania State University in 1994 after spending three years as a postdoctoral research associate at University of Colorado in Boulder. His current research centers in contemporary experimental condensed matter and materials physics, focusing on superconductivity and physics of quantum electronic materials. Systems under current study include chiral p-wave superconductor Sr2RuO4, mesoscopic and single-sheet superconductors, graphene and topological insulators, surfaces and interfaces of transition metal oxides, and strongly correlated quantum materials. Dr. Liu received an NSF Career Award in 1997 and is a fellow of American Physical Society. In China he received a NSFC Jieqing Award (Type B) in 2006 and was a Chang Jiang Jiangzuo Professor at Zhejiang University from 2007 to 2010.