Probing Charge, Spin and Thermoelectric Transport in Atomically Thin Materials

探测原子薄材料中的电荷、自旋和热电输运

• 批准号: 1708972
• 负责人: Jun Zhu
• 金额: $ 43.22万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-07-01 至 2021-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1708972&HistoricalAwards=false
• 关键词: Probing; Charge; Spin; Thermoelectric; Transport

Non-technical abstract: The silicon transistor is the fundamental building block of modern electronics, the continued shrinking of which propelled the exponential growth of computing power over the past several decades. This trend cannot continue as the size of a transistor approaches that of an atom. New electronics beyond silicon calls for new operational principles that are drastically different from that of a conventional transistor, which controls the current flow by controlling the charge of the carriers. Equally important to today's society is the development of energy-harvesting materials and devices that could convert heat to electricity efficiently. Atomically thin layered materials, which consist of layers of atoms strongly bonded within each layer but weakly bonded between layers, offer excellent opportunities to tackle both challenges. The first objective of this project is to understand how a quantum mechanical property of an electron called 'spin' propagates in atomically thin materials and to develop a new type of valve that controls an electric current flow by controlling the spin of the carriers. The second objective of this project is to understand how electric current transports and dissipates in atomically thin materials and how to engineer the surface chemistry of the materials to make them efficient heat-to-electricity converters. Knowledge gained in this research is expected to have significant impact on the development of next-generation nanoelectronics and energy-harvesting devices. The research activities train students of all levels with necessary skills to advance nanoscience and nanotechnology and promote the participation of under-represented groups. Technical abstract: This project seeks to significantly advance the fundamental understandings of charge, spin and thermoelectric transport in atomically thin transition metal dichalcogenides (TMDs) and explore their unique application potentials. One distinguishing property of TMDs that may lead to low-power electronic applications is the interlocking of the spin, valley and layer degrees of freedom in these materials. The first thrust of the project aims to systematically study spin and valley relaxation pathways in few-layer TMDs using magneto-transport measurements. The knowledge acquired is used to design and implement a novel spin-valley-layer valve in bilayer TMDs, leveraging the extensive device fabrication expertise of the PI?' lab. Measurements seek to understand its operation principles and evaluate its performances. The second thrust of the project focuses on understanding and controlling the charge and thermoelectric transport in TMD materials towards thermoelectric applications. One activity of this thrust aims to establish a much-needed quantitative understanding of the electron-phonon interactions in TMD materials by studying the temperature-dependent sheet resistance of the materials in the high-carrier density regime. A second activity exploits their band structures and surface nature to engineer desired thermoelectric responses. Experiments seek to enhance the thermopower of TMD materials using surface covalent functionalization. Measurements are supported by computations. Research carried out in this project is expected to produce timely and critical knowledge to stimulate and underpin the development of potential electronic, spintronic and thermoelectric applications of TMD materials. The research activities equip students with necessary STEM skills while summer camp activities promote science leadership and aim to broaden the reach of science to under-represented groups.

非技术摘要：硅晶体管是现代电子产品的基本组成部分，在过去的几十年里，硅晶体管的不断缩小推动了计算能力的指数增长。当晶体管的尺寸接近原子的尺寸时，这种趋势不能继续下去。硅之外的新电子学需要新的工作原理，这些原理与传统晶体管的工作原理截然不同，传统晶体管通过控制载流子的电荷来控制电流。对当今社会同样重要的是开发可以有效地将热量转化为电能的能量收集材料和设备。原子薄的层状材料，由每层内强键合但层间弱键合的原子层组成，为解决这两个挑战提供了绝佳的机会。该项目的第一个目标是了解称为“自旋”的电子的量子力学性质如何在原子级薄材料中传播，并开发一种新型阀，通过控制载流子的自旋来控制电流。该项目的第二个目标是了解电流如何在原子级薄材料中传输和消散，以及如何设计材料的表面化学，使其成为高效的热电转换器。在这项研究中获得的知识预计将对下一代纳米电子和能量收集设备的发展产生重大影响。研究活动培训各级学生必要的技能，以推进纳米科学和纳米技术，并促进代表性不足的群体的参与。技术摘要：该项目旨在显著推进原子薄过渡金属二硫属化物（TMD）中电荷、自旋和热电输运的基本理解，并探索其独特的应用潜力。可导致低功率电子应用的TMD的一个区别性质是这些材料中的自旋、谷和层自由度的互锁。该项目的第一个目标是利用磁输运测量系统地研究少层TMD中的自旋和谷弛豫路径。所获得的知识是用来设计和实施一种新型的自旋谷层阀双层TMD，利用广泛的设备制造专业知识的PI？实验室测量旨在了解其操作原理并评估其性能。该项目的第二个重点是了解和控制TMD材料中的电荷和热电输运，以实现热电应用。这一推力的一个活动旨在建立一个急需的定量了解TMD材料中的电子-声子相互作用，通过研究温度依赖的薄层电阻的材料在高载流子密度制度。第二个活动利用它们的能带结构和表面性质来设计所需的热电响应。实验试图利用表面共价官能化来提高TMD材料的热电势。测量得到计算的支持。该项目中进行的研究预计将产生及时和关键的知识，以刺激和支持TMD材料潜在的电子、自旋电子和热电应用的开发。研究活动使学生具备必要的STEM技能，而夏令营活动则促进科学领导力，旨在将科学的影响力扩大到代表性不足的群体。

项目成果

A valley valve and electron beam splitter

• DOI: 10.1126/science.aao5989
• 发表时间: 2018-12-07
• 期刊: SCIENCE
• 影响因子: 56.9
• 作者: Li, Jing;Zhang, Rui-Xing;Zhu, Jun
• 通讯作者: Zhu, Jun

Spin relaxation in fluorinated single and bilayer graphene

• DOI: 10.1103/physrevb.100.035421
• 发表时间: 2019-03
• 期刊: Physical Review B
• 影响因子: 3.7
• 作者: Susanne Wellnhofer;A. Stabile;D. Kochan;M. Gmitra;Ya-Wen Chuang;Jun Zhu;J. Fabian

Ferromagnetism in van der Waals compound MnSb1.8Bi0.2Te4

• DOI: 10.1103/physrevmaterials.4.064411
• 发表时间: 2020-06-11
• 期刊: PHYSICAL REVIEW MATERIALS
• 影响因子: 3.4
• 作者: Chen, Yangyang;Chuang, Ya-Wen;Ratcliff, William, II
• 通讯作者: Ratcliff, William, II

Atomically thin half-van der Waals metals enabled by confinement heteroepitaxy

• DOI: 10.1038/s41563-020-0631-x
• 发表时间: 2020-03-10
• 期刊: NATURE MATERIALS
• 影响因子: 41.2
• 作者: Briggs, Natalie;Bersch, Brian;Robinson, Joshua A.
• 通讯作者: Robinson, Joshua A.

Metallic Phase and Temperature Dependence of the ν=0 Quantum Hall State in Bilayer Graphene

双层石墨烯中 δ=0 量子霍尔态的金属相和温度依赖性

• DOI: 10.1103/physrevlett.122.097701
• 发表时间: 2019
• 期刊: Physical Review Letters
• 影响因子: 8.6
• 作者: Li, Jing;Fu, Hailong;Yin, Zhenxi;Watanabe, Kenji;Taniguchi, Takashi;Zhu, Jun
• 通讯作者: Zhu, Jun