Weyl and Dirac semimetals and beyond– prediction, synthesis and characterization of new semimetals

目前，凝聚态物质中发展最快的领域之一是Dirac(DSM)和Weyl(WSM)半金属的物理，这两种三维石墨烯类似物不仅具有理论上的重要性，而且作为纳米电子器件、量子计算机、超高速电路的组件具有巨大的实际应用潜力，这回答了数字经济形成的实际挑战。显然，电子结构的非平凡拓扑的所有后果还没有得到充分的研究。其中一个主要原因是缺乏这些半金属的单晶。同样明显的事实是，为了在这些材料的研究方面取得进展，需要理论和实验物理学家以及固体化学家之间的密切合作。事实上，大多数DSM和WSM都是先从理论上预测的，然后以单晶的形式生长，并通过一些确认非平凡拓扑状态的技术进行研究。这个项目的目标是理论预测，作为单晶合成，以及拓扑半金属元素和导数系统的综合研究。该项目将由来自莫斯科和德累斯顿的国际团队进行，其中包括理论和实验物理学家(莱布尼茨IFW，德累斯顿)，以及固体和材料化学家，无机合成专家(洛蒙诺索夫莫斯科国立大学化学系)。利用这种互补的专业知识，将解决拓扑半金属的化学和物理的重要问题。作为第一步，将合成和研究新的Weyl和Dirac半金属化合物。作为下一步，将合成和研究最近预测的具有多个电子能带简并点的Dirac半金属。目前，这种类型的半金属材料实际上还没有进行实验研究。本项目要解决的另一个问题是随着掺杂而改变物理性质，从而改变Weyl点和Dirac点相对于费米能级的位置。

Presently, one of the most rapidly developing field in condensed matter is the physics of Dirac (DSM) and Weyl (WSM) semimetals, 3D graphene analogs that have not only a theoretical importance, but have a significant potential for practical applications as components of nanoelectronic devices, quantum computers, ultra-high-speed circuits, which answers actual challenges of the formation of digital economy. Obviously, all the consequences of the nontrivial topology of the electronic structure have not yet been fully investigated. One of the main reason is a lack of single crystals of these semimetals. Equally obvious is the fact that, in order to achieve a progress in studying of these materials, a close collaboration between theoretical and experimental physicists and solid state chemists is needed. Indeed, most of the DSM and WSM were first predicted by theory, then grown as single crystals and investigated by a number of techniques confirming non-trivial topological states.The goals of this project are theoretical prediction, synthesis as single crystals, and comprehensive studies of topological semimetals and derivative systems. The project will be conducted by the international teams from Moscow and Dresden which includes theoretical and experimental physicists (Leibnitz IFW, Dresden), as well as solid state and materials chemists, experts in inorganic synthesis (Department of Chemistry, Lomonosov Moscow State University). With this complementary expertise the important questions of the chemistry and physics of the topological semimetals will be addressed. As the first step new Weyl and Dirac semimetals will be synthesized and investigated. As the next step Dirac semimetals with multiple degenerate points of the electron band structure, which were predicted recently, will be synthesized and investigated. At present, semimetals of this type remain practically unexplored experimentally. Another question to be addressed in the present project is the change of the physical properties with doping and consequently change of the position of the Weyl and Dirac points with respect to the Fermi level.