报告摘要：

　　Topological semimetals (TSMs) have attracted great attentions in condensed matter physics. However, the search of ideal TSMs that only the desired quasi-particles can exist around the Fermi level is still a big challenging. Taking triple-point TSM as an example, we demonstrate that the band crossing between antibonding s orbtial and bonding p orbital along a C3v symmetry can realize an ideal triple-point band crossing. By considering the general band formation model around conduction band minimum and valence band maximum in an ionic semiconductor, we have successfully targeted the ideal triple-point TSMs in NaCu₃Te₂ family compounds. Thanks to the ideal band crossing properties, we can further analysis the evolution of Fermi arc from Dirac to triple-point to Weyl semimetals for the first time. Recently, we have also extend the band crossing model from 0D point or 1D line to a 2D sphere in a 3D crystal, which may form a Dirac-nodal-sphere (DNS) system with unusual electronic properties. We also suggested several material candidates to realize such DNS states.

报告人简介：

　　黄兵，中国工程物理研究院北京计算科学研究中心特聘研究员。2005年本科毕业于吉林大学物理学院，2010年博士毕业于清华大学物理系（顾秉林、段文晖院士研究组）。2010-2015年期间曾在美国再生能源国家实验室，橡树岭国家实验室和犹他大学进行博士后研究。黄兵长期从事半导体电子结构方面的理论研究，围绕半导体物理中的基础科学问题，在对半导体的掺杂效应、合金的相图调控、拓扑材料的自旋输运和电子态调控等方面取得了多项重要成果。至今已在Phys. Rev. Lett.、Phys. Rev. X、Nature Comm.、Science Advances、JACS、Nano Letters等期刊发表论文60余篇，被引用3000次，H因子29。2018年任中央军委科技委基础加强重点项目("国防973")首席科学家。