量子论坛第二十六讲

报告题目：Chiral transport in a topological material/superconductor hybrid

报告人:Chao Zhang, Senior Professor, School of Physics, University of Wollongong, NSW, Australia

报告时间: 4月20上午10:00

报告地点: 量子楼409报告厅

报告摘要: We demonstrate some interesting chiral transport phenomena in a topological material/superconductor hybrid. (1) Specular Andreev reflection (SAR) can occur in semiconductors where the spin-orbit coupling is finite. In a hybrid of a two-dimensional electron gas with Rashba spin-orbit coupling and a superconductor and in the limit of low density or a strong spin-orbit coupling, specular Andreev reflection is finite. We show that unit electron-hole conversion is possible in a specular Andreev reflection due to the different topological structures of the equal-energy surface between electrons and holes. The SAR in the semiconductor is determined by the relative orientation of wave vector to group velocity, which can be analyzed by ray equations. (2) Electrons can undergo retro-reflection in bilayer graphene (BLG)/superconductor hybrid. The underlying mechanism for this previously unknown process is the anisotropic constant energy band contour of BLG. The electron group velocity is fully reversed upon reflection, causing electrons to be retro-reflected. (3) Strong spin-orbit coupling can result in a quantum ratchet effect.

报告人简历: Professor Chao Zhang received his PhD in physics in 1987 from City University of New York, USA. From 1987 to 1989, he was a postdoctoral fellow at Max-Planck-Institute for Solid Research in Stuttgart, Germany, working on quantum magneto-transport in semiconductor nanostructures. From 1989 to 1992, He was a research associate at Canada’s Meson Research Facility in Vancouver, working on quantum coherence and dissipation in solids. From 1993, he has been a tenured faculty member in the School of Physics, University of Wollongong, Australia. Currently he is a senior professor of physics. From 2004-2014, he served as the associate director of the Institute of Superconducting and Electronic Materials. He is a Fellow of Australian Institute of Physics. He is the associate editor of Frontier of Optolelectronics and a member of the editorial board of Scientific Report. His research interest is in the areas of quantum transport of nanostructures, terahertz photonics, nonlinear dynamics of semiconductors, graphene and topological insulators. He has published around 200 papers in refereed journals with an H-index of 30. He has received many awards including Norwegian Research Council Fellowship (1990), Norwegian Research Council Senior visiting fellowship (1996), JSPS senior fellowship (2002), and Australian Academy of Science International Award (2000, 2004).