【5.3】高能所科技创新论坛（287）Playing with Topological Insulators: Superconductivity and Strain Effects
高能所科技创新论坛（287）
报告题目：Playing with Topological Insulators: Superconductivity and Strain Effects
报告人: T.-C. Chiang 江台章(University of Illinois at Urbana-Champaign)
主持人：王焕华 研究员
时间：5月3日下午3:00
地点：物理楼B326
报告摘要：
Topological insulators are characterized by an inverted bulk band gap caused by a strong spin-orbit coupling. By analytic continuation, this gap must close at the surface and reopen outside in vacuum where the gap is noninverted (and infinite). The resulting metallic surface states, or topological states, are spin-polarized and span the bulk gap. They carry a surface spin current, largely independent of the details of the surface, which is a feature of strong interest for spintronic applications. This talk will focus on thin films of a prototypical topological insulator Bi2Se3 that are (1) made superconducting by proximity coupling to a simple superconducting substrate or (2) strained by stretching a flexible plastic film substrate. Angle-resolved photoemission and x-ray diffraction were employed to determine the electronic structure and the lattice structure. A novel "flip-chip" technique was employed to prepare epitaxial films of Bi2Se3 on the superconducting or flexible plastic substrates. We show how the topological surface states are modified under these conditions. Effects of superconducting pairing, coherence, bulk-surface coupling, and electron-lattice coupling will be discussed.
报告人简历：
江台章先生是著名的凝聚态物理学家、伊利诺伊大学香槟分校物理系教授、台湾中央研究院院士；1971年毕业于国立台湾大学，1978年在加州大学伯克利分校获得博士学位，1980年加入伊利诺伊大学香槟分校物理系。江院士在低维材料的电子态、晶格结构和动力学行为的研究上做出了开创性贡献，获得了美国物理学会的戴维逊-革末奖（Davisson-Germer Prize）。他在世界上首次制备出厚度从单层到几百层的原子级光滑均一薄膜，发现了电子在超薄膜势阱中形成驻波，实验验证了量子阱态；他在应用角分辨光电子能谱研究表面、薄膜和超晶格中也获得了开创性成果，是最早展示单晶表面原子具有不同于体内原子的芯能级结合能的人之一，这项成果引发了表面结构定量分析方法的发展；他发展了三维能带结构绘制的系统方法，根据体效应和表面效应阐明了光电子发射过程；他发展了用X射线热漫散射（TDS）研究声子色散谱的方法，该成果已经写入基础教科书；江院士发表论文与报告四百余篇，发起建造了美国同步辐射中心（SRC）的U1-NIM等实验站和先进光子源（APS）的33ID-D、E实验站，曾担任伊利诺伊大学香槟分校Frederick Seitz Materials Research Laboratory副主任、美国同步辐射中心的科学主任、台湾光子源TPS的科学顾问委员会委员、美国能源部（DOE）和自然科学基金（NSF）评委等职。
报告题目：Playing with Topological Insulators: Superconductivity and Strain Effects
报告人: T.-C. Chiang 江台章(University of Illinois at Urbana-Champaign)
主持人：王焕华 研究员
时间：5月3日下午3:00
地点：物理楼B326
报告摘要：
Topological insulators are characterized by an inverted bulk band gap caused by a strong spin-orbit coupling. By analytic continuation, this gap must close at the surface and reopen outside in vacuum where the gap is noninverted (and infinite). The resulting metallic surface states, or topological states, are spin-polarized and span the bulk gap. They carry a surface spin current, largely independent of the details of the surface, which is a feature of strong interest for spintronic applications. This talk will focus on thin films of a prototypical topological insulator Bi2Se3 that are (1) made superconducting by proximity coupling to a simple superconducting substrate or (2) strained by stretching a flexible plastic film substrate. Angle-resolved photoemission and x-ray diffraction were employed to determine the electronic structure and the lattice structure. A novel "flip-chip" technique was employed to prepare epitaxial films of Bi2Se3 on the superconducting or flexible plastic substrates. We show how the topological surface states are modified under these conditions. Effects of superconducting pairing, coherence, bulk-surface coupling, and electron-lattice coupling will be discussed.
报告人简历：
江台章先生是著名的凝聚态物理学家、伊利诺伊大学香槟分校物理系教授、台湾中央研究院院士；1971年毕业于国立台湾大学，1978年在加州大学伯克利分校获得博士学位，1980年加入伊利诺伊大学香槟分校物理系。江院士在低维材料的电子态、晶格结构和动力学行为的研究上做出了开创性贡献，获得了美国物理学会的戴维逊-革末奖（Davisson-Germer Prize）。他在世界上首次制备出厚度从单层到几百层的原子级光滑均一薄膜，发现了电子在超薄膜势阱中形成驻波，实验验证了量子阱态；他在应用角分辨光电子能谱研究表面、薄膜和超晶格中也获得了开创性成果，是最早展示单晶表面原子具有不同于体内原子的芯能级结合能的人之一，这项成果引发了表面结构定量分析方法的发展；他发展了三维能带结构绘制的系统方法，根据体效应和表面效应阐明了光电子发射过程；他发展了用X射线热漫散射（TDS）研究声子色散谱的方法，该成果已经写入基础教科书；江院士发表论文与报告四百余篇，发起建造了美国同步辐射中心（SRC）的U1-NIM等实验站和先进光子源（APS）的33ID-D、E实验站，曾担任伊利诺伊大学香槟分校Frederick Seitz Materials Research Laboratory副主任、美国同步辐射中心的科学主任、台湾光子源TPS的科学顾问委员会委员、美国能源部（DOE）和自然科学基金（NSF）评委等职。
高能所科研计划处、党政联合办、教育处
2018年4月26日
2018年4月26日
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