| 报告题目： |
Quantum transport in topological semimetals |
| 报告人： |
卢海舟 副教授 |
| 报告人单位： |
南方科技大学 |
| 报告时间： |
2016年4月8日上午9:30 |
| 报告地点： |
国家脉冲强磁场科学中心B206 |
| 报告摘要： |
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Topological semimetal is a three-dimensional topological state of matter, in which the conduction and valence energy bands touch at a finite number of Weyl nodes. The Weyl nodes always appear in pairs, and carry opposite chirality and linear dispersion, much like 3D analogue of graphene. Topological semimetals also host paired monopoles of Berry curvature in momentum space and Fermi arcs.
In this talk, I will cover several quantum transport effects that have been observed recently in topological semimetals. Weak antilocalization, which can give rise to a negative magnetoconductivity proportional to the square root of magnetic field at low temperatures. We have a systematic theoretical study on the weak antilocalization in topological insulator, 2D materials, and topological semimetals. The theory has been applied in recent experiments on the topological Weyl semimetal TaAs. Chiral anomaly, which is expected to give a positive quadratic-B magnetoconductivity (i.e., negative magnetoresistance) in parallel magnetic fields. We have experimentally observed the effect in the topological semimetal Cd3As2. The chiral anomaly is also predicted to give a linear-B magnetoconductivity in the quantum limit at high fields. However, all experiments on Weyl and Dirac topological semimetals show a negative magnetoconductivity in high fields. We show that the high-field positive magnetoconductivity may not be a compelling signature of the chiral anomaly and will be helpful for interpreting the inconsistency in the recent experiments and earlier theories. |
| 报告人简介： |
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卢海舟，2002年于兰州大学获得硕士学位，2007年于清华大学高等研究所获博士学位，导师朱邦芬院士。同年赴香港大学做博士后研究，合作导师沈顺清教授，2012年转为研究助理教授。 现在为南方科技大学物理系副教授。目前主要从事凝聚态物理的研究，特别是量子输运。最近的研究兴趣是利用量子场论方法研究新材料中的量子态和量子输运，包括拓扑绝缘体/半金属/超导体，二维层状材料，弱局域化，量子自旋和反常霍尔效应等。曾使用费曼图技术，系统地研究了二维有质量狄拉克电子的量子输运行为。多个理论工作被实验支持和广泛应用。在物理学期刊发表了30 余篇论文，总引用1200多次，H指数为15，有5篇论文引用超过100次，单篇论文最高引用超过200次。长期为各种物理学期刊审稿。 |
