层状拓扑晶态材料可控生长及强磁场下奇异输运性质的研究

Spin injection source is the key component of spintronic devices, and currently often uses the structure of ferromagnetic metallic layer/tunneling layer/spin channel layer. However, there exists problems such as conductance mismatch, low efficiency of spin injection and non-all-electrical manipulation. Recently topological electronic state has become one of the hot topics in the multi-disciplinary of condensed matter physics, quantum materials science and information electronics. Its characteristic is that the electronic structure of the crystalline materials has the abnormal topological number, which leads to the special electronic states such as topological insulator surface states, Weyl Femion and Fermi arc. Topological electronic state possesses the unique spin helicity and hence is the new choice for all-electric spin injection source. In this project, we propose to carry out the controllable growth of layered topological crystalline 2D materials and their device fabrication integrated with graphene channel. Based on our previous study on crystal growth of topological semimetals, transport under the pulsed intense magnetic field, and spintronic prototypical devices of topological insulators, we perform the experimental studies on controllable growth and optimization of topological materials, exotic transport properties of transistor devices under the stable intense magnetic field, and the spin-momentum locking of surface state electrons. We expect that we are able to observe the spin-related exotic physical effects in spintronic prototypical devices by using topological crystalline materials layer/tunneling layer/graphene channel layer contact structure, which would provide the important scientific parameters for the novel spin transistor device applications.

自旋注入源是自旋电子器件的关键部件，目前常采用铁磁金属层/隧穿层/自旋沟道层的构型，但存在电导失配、自旋注入效率低以及非全电学操控等问题。拓扑电子态是近期凝聚态物理学、量子材料科学及信息电子学等多学科领域研究关注的热点之一，其特征是晶态材料的电子结构具有反常拓扑数，这导致拓扑绝缘体表面态、外尔费米子和费米弧等独特的电子态。拓扑电子具有独特的自旋螺旋性，是全电学自旋注入源的新选择。本项目拟开展层状拓扑晶态二维材料的可控生长及其与石墨烯沟道的器件制备研究，在我们前期拓扑半金属生长、脉冲强磁场输运和拓扑绝缘体自旋原型器件研究的基础上，集中开展拓扑材料可控生长和优化、晶体管器件在稳态强磁场下的奇异输运性质及表面态电子自旋-动量锁定等方面的实验研究。我们期望利用拓扑晶态材料层/隧穿层/石墨烯沟道层的接触构型，在自旋原型器件中观测到自旋相关的奇异物理效应，为新型的自旋晶体管器件应用提供重要的科学依据。

我们在本项目所支持的层状拓扑晶态二维材料及相关领域开展了系统工作，完成了预定的研究任务，取得了若干有创新性的研究成果。三年来发表SCI论文28篇，其中第一作者或（共同）通讯作者论文18篇，包括发表在Adv. Mater.、Phys. Rev. Lett.、Nano Lett.、ACS Nano、Adv. Electron. Mater.、Appl. Phys. Lett.、Chin. Phys. Lett.等国际、国内一流期刊上的论文，并编写专著《Spintronic 2D Materials: Fundamentals and Applications》一章（出版社Elsevier），获得授权国家发明专利3项，自主搭建一套低温强场光电集成输运测量系统，培养5名博士生及2名硕士生毕业。项目申请人于2018年获得基金委优秀青年基金。在该项目支持下，我们主要制备了高质量的拓扑单晶块材及大面积薄膜单晶结构，主要材料类型有拓扑狄拉克半金属ZrSiSe、ZrTe5、拓扑相变材料(Bi,In)2Se3及拓扑外尔半金属WTe2单晶薄膜等，利用微加工技术和稳态强磁场输运测量实现了基于拓扑材料的自旋原型器件及外场调控。同时深入探索了诸如复杂氧化物界面、氧化物二维电子气等其它量子耦合体系的新奇物理现象。该项目的研究为拓扑二维电子材料及其它体系在自旋电子器件的应用奠定了坚实的基础。