德国维尔茨堡大学的Laurens W. Molenkamp教授将于6月9日上午来我所学术交流，并在“黄昆半导体科学技术论坛”上作第124期报告，望相关领域的科研人员及研究生准时参加!

报告题目: Spin Hall effects in HgTe Quantum Well Structures

报告人: Prof. Dr. Laurens W. Molenkamp (Universität Würzburg, Germany)

时间: 2010年6月9日(星期三) 上午 10:00

地点: 中国科学院半导体研究所学术会议中心

Abstract：Spin-orbit interaction in semiconductors causes many interesting and potentially useful transport effects, such as e.g. the presently very topical spin-Hall effect. So far no direct evidence for a ballistic, intrinsic SHE (i.e. resulting from the band structure) has been obtained by transport experiments. Here, we demonstrate that in specially designed nanostructures, which are based on narrow gap HgTe type-III (a.k.a. inverted) quantum wells, a detection of the spin signal is possible via non-local voltage measurements.

Recently, it was pointed out that such inverted HgTe structures are topologically non-trivial insulators, in which the quantum spin Hall insulator state should occur. In this novel quantum state of matter, a pair of spin polarized helical edge channels develops when the bulk of the material is insulating, leading to a quantized conductance. I will present transport data provide very direct evidence for the existence of this third quantum Hall effect: when the bulk of the material is insulating, we observe a quantized electrical conductance. Apart from the conductance quantization, there are some further aspects of the quantum spin Hall state that warrant experimental investigation. Using non-local transport measurements, we can show that the charge transport occurs through edge channels - similar to the situation in the quantum Hall effect. However, due to the helical character of the quantum spin Hall edge channels, inhomogeneities in the potential profile of the experimental devices have a much stronger effect on the transport properties. Moreover, the quantum spin Hall edge channels are spin polarized. We can prove this fact in split gate devices that are partially in the insulting and partly in the metallic regime, making use of the occurrence of the non-quantized metallic spin Hall effect to convert the magnetic spin signal into an electrical one.

报告人简介：Laurens W. Molenkamp教授，1985年11月在荷兰格罗宁根大学（University of Groningen）获得博士学位，1985年至1994年任荷兰飞利浦实验室“纳米结构中量子输运及单电子效应”项目负责人；1994年11月起任德国亚琛理工大学实验物理学教授，1999年4月起任德国维尔茨堡大学物理系教授、实验物理三所所长。Molenkamp教授是半导体量子输运、自旋电子学研究领域的国际著名专家，是Physical Review B, Physical Review Letters, Applied Physics Letters, Nature, Science等学术杂志的审稿人，2001至2007年曾担任Physical Review Letters编委，2002年起任Semiconductor Science and Technology主编。2009年7月接受聘请任中国科学院半导体所荣誉教授。

科技开发处