Prof. Myung-Hwa Jung: Topological Insulators
Povzetek:
Topological Insulators
Prof. Myung-Hwa Jung, Department of Physics, Sogang
University, Seoul, Korea
A topological insulator is a material that has a metallic surface state inside an insulating bulk gap, meaning that electrons can only move along the surface of the material. The gapless surface state gives rise to exotic phenomena such as the quantum spin Hall effect, weak antilocalization, and quantum oscillations induced by two-dimensional Dirac electrons. In addition, the topological surface state is protected by the time reversal symmetry, so that elastic backscattering is forbidden and high mobility can be realized in the surface state. These characteristics appeal the basic platform for not only fundamental physics but also various applications such as spintronics and quantum computing. However, it is difficult to observe the surface state in experiments because the Fermi level is normally located at the bulk bands due to the intrinsic defects of the samples. There have been lots of efforts to locate the Fermi level in the topological transport regime between the bulk conduction band minimum and the bulk valence band maximum. The simple way to tune the Fermi level is doping other elements like transition metals. Here, I will talk about the exotic quantum phenomena coming from the surface state in topological insulators and the non-magnetic versus magnetic doping effects in Bi2Se3 and Bi2Te3 topological insulators, based on experimental results.
