强磁场下非中心对称半导体材料Te新颖物性研究

Tellurium (Te) is a simple elemental semiconductor with narrow band gap. Recently, Te has attracted substantial interest in many hot topics in condensed matter physics, including topological properties, quantum transport and spintronics, arising from its non-centrosymmetric crystal structure, strong spin-orbit coupling, etc. High magnetic field provides an ideal technique for the investigation on the novel physical properties of chiral material Te with helical structure. In this project, by utilizing multiple characterization methods under high magnetic fields in High Magnetic Field Laboratory of the Chinese Academy of Science, we would like to study the high pressure and quantum confinement effects on the electronic structure and transport properties of Te, for example, to verify the possible pressure-induced topological phase transition from semiconductor to Weyl semimetal, and to unveil the emergence of novel quantum transport properties in two-dimensional Te under high magnetic fields. In addition, we would further investigate the novel magneto-electric coupling behaviors in Te and to gain some insights into the microscopic mechanisms of the current induced magnetization. The fulfillment of this project will be helpful to reveal the relation between the special crystal structure and novel physical properties of Te, to broaden the community of the topological materials, two dimensional semiconductors and spinctronics, and will provide useful references for the investigation of physical properties under high magnetic fields.

碲(Te)是一类窄带隙单质半导体材料。由于其非中心对称的晶体结构以及强自旋-轨道耦合相互作用等特性，近年来，Te在拓扑物性、量子输运以及自旋电子学等多个凝聚态物理学的前沿领域引起了广泛的研究兴趣。强磁场在以上诸多领域展现出的巨大作用使得其成为研究Te这类具有螺旋结构的手性材料新颖物性的绝佳手段。本项目将充分依托中国科学院强磁场科学中心强磁场环境下的多种表征手段，研究压力、量子限域效应等对Te电子结构及输运性质的影响，验证Te在高压下是否会出现半导体到外尔半金属的拓扑相变，以及探究其二维结构在强磁场下所展现出的新颖量子输运性质。与此同时，阐明Te中电流诱导磁效应这种新颖磁电耦合现象的微观机制和调控规律。我们希望通过本项目的开展，揭示Te特殊晶体结构与新颖物性之间的关联，丰富拓扑材料、二维半导体以及自旋电子学等研究领域的材料选择，为强磁场下材料物性研究提供有用的参考。

在本项目的支持下，我们围绕厘清拓扑材料特殊晶体结构与拓扑物性关联，实现低维量子材料磁电特性的有效调控这两个基本科学问题开展了系统的研究。取得的主要创新成果包括：1）依托稳态强磁场实验装置，揭示半导体碲中由外尔费米子诱导的丰富拓扑输运特性，成功将外尔物理从半金属拓展到更具可调性和应用价值的半导体体系；2）实验确证笼目晶格材料FeSn中存在反铁磁狄拉克态；3）通过界面应力工程，在低维关联氧化物中实现电子相的摩尔调控；4）通过异质结构构筑显著增强石墨烯量子霍尔效应的鲁棒性。在该项目执行期间，共发表SCI论文9篇，包括1篇Nat. Phys.，1篇PNAS，2篇Nano Lett.和2篇Chin. Phys. Lett.。