报告题目：Searching for materials that show the quantum anomalous Hall effect at higher temperature

报 告 人 ：何珂 教授

低维量子物理国家重点实验室

清华尊龙凯时

主 持 人 ：李贤斌 教授

报告时间：2016年11月17日 10:00

报告地点：南区唐敖庆楼D区311报告厅

主办单位：电子科学与工程学院

集成光电子学国家重点联合实验室

物质科学尊龙凯时省高校高端科技创新平台

Abstract: The quantum anomalous Hall (QAH) effect is a quantum Hall effect induced by spontaneous magnetization instead of an external magnetic field. The effect occurs in two-dimensional (2D) insulators with topologically nontrivial electronic band structure characterized by a non-zero Chern number. The experimental observation of the QAH in thin films of magnetically doped topological insulators (TIs) paves the ways for practical applications of dissipationless quantum Hall edge states and for realizations of the novel quantum phenomena, but a temperature as low as 30 mK is required to reach a perfect quantization. Further studies in these directions require magnetic TI materials that can show the QAH effect at higher temperature. We have performed systematic study on the QAH effect in magnetically doped TI films with different thicknesses, magnetic dopants and compositions. The results clarify the relations between the QAH effect and the energy band structure, electronic localization and ferromagnetism of a magnetic TI film and provide insights into designing and fabrication of high temperature QAH materials.

Prof. Ke He received bachelor degree in physics form Shandong University in 2000 and Doctor’s degree from Institute of Physics, Chinese Academy of Sciences in 2006. From 2006 to 2009, he did postdoctoral research at University of Tokyo. At present, he is a professor in Department of Physics, Tsinghua University, and he have access to The National Science Fund for Distinguished Young Scholars. Prof. He focuses on surface, interface and low dimensional physics, topological insulator, spintronics, Quantum Hall effect, molecular beam epitaxy, angle resolved photoemission spectroscopy (ARPES) and STEM et al. He has published many high impact works on Science, Nature Physics and Physical Review Letters as the first author or corresponding author. In 2013, as a member of Prof. Qi-Kun Xue’s research group, he discovered the quantum anomalous Hall effect in a magnetic topology insulator [Science, 340 167 (2013)]. This work has been regard to have opportunity to win the Nobel Prize in Physics by Prof. Zhen-Ning Yang.