报告题目：Photoninduced Weyl half-metal phase and spin filter effect from topological Dirac semimetals

报告人：邓明勋博士（华南师范大学）

主持人：邓伟胤博士

报告时间：2019年11月1日（星期五）下午3:30 

报告地点：物理楼（18号楼）二楼213室学术报告厅

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                                  物理与光电学院

                                     2019年10月25日

附件：

内容摘要：

Recently discovered Dirac semimetals (DSMs) with two Dirac nodes, such asNa₃Bi and Cd₂As₂, are regarded to carry the Z₂topological charge in addition to the chiral charge. Here, we study theFloquet phase transition of Z₂ topological DSMs subjected to abeam of circularly polarized light. Due to the resulting interplay of thechiral and Z₂ charges, the Weyl nodes are not onlychirality-dependent but also spin-dependent, which constrainsthe behaviors in creation and annihilation of the Weyl nodes in pair.Interestingly, we find a novel phase: One spinband is in Weyl semimetal phasewhile the other spinband is in insulator phase, and we dub it Weyl half-metal(WHM) phase. We further study the spin-dependent transport ina Dirac-Weyl semimetal junction and find a spin filter effect as a fingerprintof existence of the WHM phase. The proposed spin filter effect, based on theWHM bulk band, is highly tunable in a broad parameter regime and robustagainst magnetic disorder, which is expected to overcome theshortcomings of the previously proposed spin filter based on the topologicaledge/surface states. Our results offer a unique opportunity to explore thepotential applications of topological DSMs in spintronics.

报告人简介：邓明勋，2018年毕业于南京大学物理学院，师从邢定钰院士、盛利教授，现为华南师范大学特聘副研究员、青年英才；博士期间曾获得“固体微结构物理国家重点实验室优秀毕业生奖”，主要研究拓扑材料中的杂质散射效应、量子输运以及含时驱动诱导的拓扑现象，已发表SCI论文23篇，其中Phys. Rev. Lett. 2篇, Phys. Rev. B 10篇, New J. Phys. 1篇。最近，与南京大学邢定钰院士、盛利教授以及华南师范大学王瑞强教授合作，提出Weyl half-metal的概念，相关文章被PRL接收发表。