Title: Topological Insulators and Topological Superconductors 

Speaker: Shun-Qing Shen (Professor, Department of Physics, the University of Hong Kong) 

Time: June 5,2014,10:00AM

Venue:Academic Conference Center, IOS, CAS

Abstract: Topological insulator is an insulator that always has a metallic boundary. These metallic boundaries originate from the topology of the band structure of solids, which is insensitive to the geometry of system and cannot change as long as the material remains insulating. Such materials, usually with some symmetry, can be characterized by topological invariants. Their properties are robust, and insensitive to perturbations without breaking the symmetry. Since the theoretical prediction in 2004, more materials have been found to possess such topological properties. The concepts of topological insulators have been generalized from two dimensions to three and one dimensions, from insulators to superconductors, optical crystals and cold atom systems, and become an important branch of condensed matter physics. These topological materials possess nontrivial properties such as dissipationless spin currents, with potential applications in next generation of electronic devices. For topological superconductors, the nontrivial properties of boundary states also give rise to special effects. For instance, the elementary excitation at the ends of a one-dimensional quantum wire is a massless elementary particle with neutral charge, with important applications in quantum computations. In this talk, I will introduce some basic concepts of topological insulators and topological superconductors, with a simple and unified description for a large family of topological insulators, and also potential applications of these materials. 

Biograpy: Professor Shun-Qing Shen, an expert in the field of condensed matter physics, is distinguished for his research works on topological insulator, spintronics of semiconductors, quantum magnetism and orbital physics in transition metal oxides, and novel quantum states of condensed matters. He proposed theory of topological Anderson insulator, spin transverse force, resonant spin Hall effect and theory of phase separation in colossal magnetoresistive (CMR) materials. He proved existence of antiferromagnetic long-range order and off-diagonal long-range order in itinerant electron systems. He has published a single-authored monograph, Topological Insulators (Springer, 2012), which is the first book on the topic, and more than 100 papers in Physical Review and Physical Review Letters. He was awarded Croucher Senior Research Fellowship (The Croucher Award) in 2010, and 2012-2013 Outstanding Researcher Award of The University of Hong Kong.