【作者】 李敏；

【导师】 龚士静；

【作者基本信息】 华东师范大学 ， 物理电子学， 2021， 硕士

【摘要】 近年来,集成电路逐步向小型化、高密度、低功耗、非易失、高速率方向发展,二维材料由于维数降低和量子限制效应表现出不同于体相材料的优异特性,成为未来信息技术领域备受关注的对象。目前,实验上已经发现了多种二维材料,如石墨烯、过渡金属硫化物、金属氧化物和二维磁体等。然而,现代技术和应用要求材料具有多功能效应以实现功能集成,单一材料不经过修饰很难实现多种功能。二维层状材料可以通过应变、门控、离子掺杂,搭建异质结等不同方法灵活地调控其电、磁、以及光学性质,从而实现多种功能效应。探索二维材料性质的调控方法以及调控效果成为物理电子学领域一个重要的研究方向。本文利用基于密度泛函理论的第一性原理计算方法,以典型的二维单层过渡金属硫化物MX₂（X=Mo,W;X=S,Se,Te）和铁磁金属Fe₃Ge Te₂为例,探究了电学方法（外电场、注入电荷、铁电极化反转等）对二维层状材料本征电学、谷电子学和磁学性质的调控,为自旋电子学的发展以及新型多功能器件的应用提供了一定的理论指导。文章主要包括两部分内容:1、我们研究了六种H相MX₂单层的本征电学性质,分析了外加垂直电场对MX₂单层Rashba自旋劈裂的调控。利用外电场和电子掺杂,探究了近自由电子态的移动对MX₂单层能带结构的影响。另外,我们还对比了1T’相Mo Te₂与WTe₂单层中的近自由电子态性质。最后,简要解释了电荷掺杂在Mo Te₂单层中诱导出铁磁性和谷极化的原因。2、我们研究了Fe₃Ge Te₂单层的本征铁磁性和磁各向异性,通过将Te原子替换成同族的Se原子,分析了Fe₃Ge Te₂单层的磁各向异性对Te原子的自旋轨道耦合作用的依赖性。利用空穴掺杂及搭建铁磁/铁电异质结（Fe₃Ge Te₂/In₂Se₃）的电学方法,对Fe₃Ge Te₂单层的磁各向异性进行了调控。更多还原

【Abstract】 Recent years,integrated circuits（IC）are gradually developing towards miniaturization,high density,low power consumption,non-volatile and high speed.Due to dimensionality reduction and quantum confinement effect,two-dimensional materials exhibit excellent properties different from bulk material,and become the focus of attention in the field of information technology.At present,a variety of two-dimensional materials have been found experimentally,such as graphene,transition metal dihalides,metal oxides and two-dimensional magnets.However,modern technology and applications require materials to possess multifunctional effects to achieve functional integration,and it is difficult for a single material to achieve multiple functions without modification.The electrical,magnetic,and optical properties of two-dimensional layered materials can be flexibly regulated through different methods,such as strain,gating,ion doping and heterojunction construction,so as to achieve a variety of functional effects.In the field of physical electronics,it has become an important research direction to explore the regulation methods and effects of the properties of two-dimensional materials.In the article,by using the first principles calculation method based on density functional theory,a typical two-dimensional transition metal dihalides MX₂（X=Mo,W;X=S,Se,Te）and ferromagnetic metal Fe₃Ge Te₂ were taken as examples,in order to investigate the regulation of intrinsic electronic,valleytronic and magnetic properties of two-dimensional layered materials,with electrical methods（such as external electric field,charge injection,ferroelectric polarization reversal）,which provides certain theoretical guidance for the development of spintronics and the application of new multifunctional devices.The article mainly includes two parts:1.The intrinsic electronic properties of six MX₂ monolayers of H phase is studied,and we analyze the regulation of external electric field on Rashba spin splitting.The movement of near free electron states on the band structure of MX₂ monolayer with external electric field and electron doing.In addition,we also compare the variation of nearly free electron states in the distort T phase Mo Te₂ monolayer and WTe₂ monolayer with corresponding H phase.Finally,the reason of ferromagnetism and valley polarization induced by charge doping in Mo Te₂ monolayer is explained simply.2.We investigate the intrinsic ferromagnetism and magnetic anisotropy of Fe₃Ge Te₂ monolayer,and analyze the dependence of the magnetic anisotropy of Fe₃Ge Te₂ monolayer on the spin-orbit coupling of Te atoms by replacing Te atom with Se atom of the same group.With the electrical method of hole doping and the construction of ferromagnetic/ferroelectric heterojunction（Fe₃Ge Te₂/In₂Se₃）,the magnetic anisotropy energy of Fe₃Ge Te₂ is modified.更多还原