*일시: 11월 1일(목) 오후 4시30분
*장소: 베어드홀 320호 (물리학과 세미나실)
*연사: 정명화 교수(서강대 물리학과)
*제목: Rare-earth doped magnetic topological insulators
There are many interests to achieve long-range magnetic order in topological insulators of Bi2Se3 or Bi2Te3 by doping magnetic transition metals such as Fe and Mn. The transition metals act as not only magnetic dopants but also electric dopants because they are usually divalent. However, if the doping elements are rare-earth metals, which are trivalent, only magnetic moments can be introduced. Here, I would talk about the exotic quantum phenomena coming from the surface state in topological insulators and the magnetic doping effects into Bi2Se3 and Bi2Te3 topological insulators, based on experimental results. We observed magnetic phase change to antiferromagnetic phase by doping. This paramagnetic to antiferromagnetic phase transition agrees with the density functional theory calculations showing a weak and short-ranged magnetic coupling via the intervening Te ions.