Magnetic topological semimetals

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讲座内容：

In a 3D solid, the lowenergy excitation of the linearly dispersive crossing bands satisfies the Dirac(Weyl) equation. Such band crossing is named as Dirac (Weyl) node (DN or WN),and such solid is known as the topological (Dirac or Weyl) semimetal (DSM orWSM), which exhibit remarkable features, such as Fermi arcs, magnetic monopolesand Weyl anomaly. In this talk, I will introduce three works on magnetictopological semimetals. 1. Ferromagnetic HgCr2Se4, theonly known of double-Weyl semimetal, where the quantum anomalous Hall effectcan be achieved in its quantum-well structure. 2. The long-pursuing ideal WSMrealized in the non-collinear magnetic GdSI. We demonstrate that fruitfultopological phases can be realized in a specific honeycomb lattice, includingthe ideal Weyl semimetal, double-Weyl semimetal, 3D strong topologicalinsulator, nodal-line semimetal, and a novel semimetal consisting of both Weylnodes and nodal-lines. 3. Anti-ferromagnetic (AFM) DSM realized in the interlayerAFM EuCd2As2. In this work, we generalize the concept ofDSM to the magnetic space groups (MSGs), and define a new category of DSM intype IV MSGs. Many exotic topological states, such as the triple pointsemimetal and the AFM topological insulator holding of the half-quantum Halleffect can be derived from such AFM DSMs by breaking certain symmetry,providing an ideal platform to study topological phase transitions.

主讲人介绍：

徐刚， 2010年获中国科学院物理研究所博士学位，2010-2012年任中科院物理所助理研究员，2012-2016在美国斯坦福大学做访问研究，现在华中科技大学国家脉冲强磁场中心工作，入选第十三批千人计划“青年项目”。主要从事新奇物性和材料的第一性原理计算和理论研究。研究兴趣包括：强关联与非常规超导、拓扑物质态，新型二维功能材料等，已发表学术论文36篇，总引用4500多次， H因子22；其中Nature子刊、PRL等国际顶级期刊16篇，另有两篇论文入选“2008年中国百篇最具影响国际学术论文”。重要成果：1）成功预言了铁基超导母体材料中的条纹状反铁磁基态——铁基超导获得"国家自然科学一等奖"的代表性工作之一2）把凝聚态中电子态按照拓扑分类的概念从绝缘体推广到了半金属，首先提出双外尔半金属的概念，开启了凝聚态中Weyl费米子的研究热潮，引用达650多次。

发布时间：2018-05-31 14:34:42