新型二类狄拉克半金属中奇异输运特性的实验研究

Topological materials have stimulated widespread interest in condensed matter physics. Type-II Dirac semimetal (DSM) is a brand new classification of topological matters. It holds strongly tilted Dirac band dispersions and a series of exotic transport properties and potential applications are expected. However, many predicted characteristics are still not observed because of the imperfection of the band structure in recent studied type-II DSMs. We plan to grow the single crystals of new type-II DSM candidates with optimized band structure and transport properties. By low-temperature transport measurement, the transport properties of these materials will be systematically investigated, including several novel phenomena such as anisotropic chiral anomaly and Klein-tunneling in momentum space which are resulted from the exotic topological band structures. In addition, the evolution of these phenomena based on the changing of external conditions such as temperature, magnetic field and material band dispersions will be further studied in order to deeply reveal the intrinsic physical properties of type-II DSMs. This project will benefit the present interest in the fundamental researches in topological matters as well as the potential applications based on those topological properties.

新型拓扑材料是当前凝聚态物理的研究热点。二类狄拉克半金属是近年被提出的一类全新拓扑物态，理论预言其特殊的倾斜狄拉克型能带色散会带来一系列奇异的输运特性和潜在的应用前景。然而，目前由于材料能带和性能还不够完善，其诸多的奇异性质难以被实验观测和证实。本项目计划通过多种晶体生长方法制备高质量的新型二类狄拉克半金属单晶样品，其能带结构和输运性能较现有研究体系更为优化。并通过低温强磁输运测量对合成样品的输运行为进行系统的测量和分析，研究其中由奇特的拓扑能带构型导致的诸如各向异性手性反常、动量空间Klein隧穿等奇异的物理效应。进一步的，分析相关物理效应随材料能带结构参数、外界温度、磁场等条件变化的响应规律，对本征的二类狄拉克半金属物理性质进行深入的研究分析。本项目对热点关注的拓扑物态基础科学研究和探索相关拓扑物性的潜在应用价值都有着重要意义。

新型拓扑材料是当前凝聚态物理的研究热点。尤其对于二类狄拉克半金属等近年来提出的全新拓扑概念，越来越多的实际拓扑体系被发现，并有众多的奇异拓扑物性被预言。本项目中，我们通过低温电输运、磁性测量、角分辨光电子能谱、扫描隧道显微镜等多种实验手段，针对二类狄拉克半金属、本征磁性拓扑绝缘体、结线半金属等新型拓扑材料开展能带优化与物性调控研究工作，对热点关注的拓扑物态基础科学研究和探索相关拓扑物性的潜在应用提供了材料平台。基于本项目，申请人以第一作者/通讯作者在Advanced Materials、ACS Nano等国际一流学术期刊上共发表SCI论文10篇，其中两篇论文被AIP编辑部选为编辑推荐论文。