题 目：Nodal Chain in Electronic and Phononic Systems
报告人：杨声远 副教授，新加坡科技设计大学
时 间：2021年06月29号（星期二）上午10:30
地 点：理科楼物理学院LE201
邀请人：王 锐
报告摘要：
Topological states of matter are a focus of current physics research. In topological semimetals, the state is characterized by band degeneracies around the Fermi level, which determine the low energy quasiparticles and hence most physical properties of the system. These degeneracies can take the form of nodal points, loops, and surfaces. In this talk, I will focus on the nodal loops and discuss our works on their characterization based on the topology, type of dispersion, and order of dispersion. Particularly, the loops can form extended chains in the momentum space. We show that fourfold degenerate Dirac chains can be enforced by certain nonsymmorphic space group symmetries for electronic systems. Recently, we find that a different symmorphic nodal chain can also be enforced in phononic systems, manifesting the unique characters of phonons. We identify concrete materials for realizing these nodal chains and suggest their experimental signatures.
报告人简介：
杨声远，江苏省南京人。2001-2002年: 清华大学电气自动化专业。2002-2005: 香港大学，数学物理专业，获理学学士。2005-2011年：得克萨斯大学奥斯汀分校，凝聚态物理，获博士学位。2011-2013年：休斯敦CGG Veritas US Services公司工作，地质分析成像工程师。2013年起在新加坡科技设计大学担任助理教授，副教授。以往的研究课题包括磁性材料的磁动力学，二次谐波的发射理论，反常霍尔效应，二维材料/拓扑材料的物理性质。目前的研究方向包括拓扑半金属，拓扑绝缘体，二维材料和纳米结构的物理性质，电子晶体，自旋和谷电子学，量子输运等。
