아래와 같이 콜로퀴움을 개최하오니 많이 참석해 주시기 바랍니다.
4시 20분부터 제1과학관 31214 e+강의실에서 다과를 준비하오니 많은 참석 부탁드립니다.
아 래
제목: 3D topological insulators with magnetic impurities
연사: 정 명 화 교수님 (서강대학교 물리학과, 91학번 동문)
일시: 2014년 11월 19일(수) 오후 4:30
장소: 제1과학관 31214 첨단e+강의실
초록: A2B3 (A=Bi, Sb and B=Se, Te) is a new family of three-dimensional topological insulators. A lot of efforts such as chemical doping have been made to manipulate the original topological states. First, we report the doping effect of magnetic Mn ion in Bi2Se3, that is Bi2-xMnxSe3 (x = 0, 0.03, 0.05, 0.09, and 0.15). We observe the tuning of charge carriers in Bi2Se3 from n type to p type by Mn doping at x = 0.05, where the electrical resistivity shows non-metallic behavior at low temperatures. Second, we report the doping effect of magnetic Fe ion in Bi2Te3, that is Bi2-xFexTe3 (x = 0, 0.08, 0.15, 0.2, 0.25 and 0.3). We intentionally generate n-type carriers by putting a small amount of Te excess, which compensate for the holes from the antisite defects. The Fe doping causes the n-type carrier density to be decreased with increasing x, and finally be changed into p type at x = 0.3, where the carrier mobility suddenly drops. Furthermore, we have studied Ce- and Gd-doped Bi2Te3 systems, which will be discussed for future spintronics application.
