报告题目：From Weyl semimetal to Dirac semimetal in HgCr2Se3.5Te0.5

报 告 人：虞祥龙 博士

工作单位：南方科技大学

报告时间：2017年4月26日（周三）下午2:00

报告地点：博逸楼401会议室

内容简介:

Weyl semimetal has recently attracted enormous attention due to their unusual features. So far, this novel state has been predicted theoretically and confirmed experimentally in several materials, such as HgTe, LaPtBi, Y2Ir2O7, TaAs, TaP, NbAs, NbP and HgCr2Se4. Doping plays an important role in the research of condensedmatter materials. However, its influence on the Weyl semimetal has been little investigated. Here, we present detailed first-principles and theoretical studies on HgCr2Se4  with doping of Te atoms at the Se sites. A special case where only one pair of crossing points locates at the Fermi level is realized in HgCr2Se3.5Te0.5 where one of the Se atoms in the primitive unit cell is replaced by a Te atom. A further study of k•p theory shows that the two points constitute a pair of Weyl nodes with opposite chiralities in the momentum space, and only one edge state and one single Fermi arc are obtained at each boundary of a film. Moreover, through investigations and analyses of different doping cases of HgCr2Se3.5Te0.5 , we find that when the type of doping induces inversion symmetry or positional disorder, the Weyl nodes transform into Dirac points resulting in a change from a Weyl semimetal to a Dirac semimetal.

个人简历：

虞祥龙博士，2010年于青岛大学物理科学学院应用物理学专业获理学学士学位，2015年于中科院固体物理所获理学博士学位，2015年至今，南方科技大学博士后。主要研究兴趣为使用第一性原理计算和密度泛函理论研究强电子关联体系，以及Weyl半金属中的电子关联效应。