Controlling Valley and Spin-Orbit Coupling in Graphene and Bilayer Graphene Nanostructures

非技术摘要本项目旨在探索石墨烯和双层石墨烯的物理和应用，双层石墨烯由一层或两层碳原子排列在六边形晶格中组成。碳原子的排列导致了独特的电子特性，这些特性可能成为新一代低功耗纳米电子学和新型电子学的基础。这些新设备将利用电子自旋，电子的量子力学性质，而不是电子电荷，如传统的电子学。研究活动将为研究生和本科生提供先进的技术，方法和沟通技巧，以促进学术或工业环境中纳米科学和纳米技术的进步。研究团队通过3小时的研讨会与高中生（10-12年级）互动，结合讲座，演示，实验室参观和动手活动，介绍原子薄材料的特性和应用。该研讨会是通过与宾夕法尼亚州立大学科学U领导力夏令营和向上的约束（UB）和向上的约束移民（UBM）计划，特别是针对来自低成就PA学区的学生的伙伴关系提供给参与者。 自旋、谷、层及其紧密耦合是二维六方晶体的显著特征，对这些特征的研究可以带来新的基本认识和潜在的应用。研究活动包括两个方向，分别旨在控制双层石墨烯纳米结构中的谷自由度和石墨烯中的局部自旋轨道耦合。第一个推力采用双分裂门控器件研究一个新的一维边缘模式（扭结态）产生的两个相反偏置的双层石墨烯的线结的奇异属性。在磁场和超导电极存在下的扭结态的研究阐明了它与量子霍尔磁性和近端超导性的相互作用。第二个推力利用吸附原子功能化，特别是双金属，工程师在石墨烯的局部自旋轨道耦合，并研究其对自旋输运和自旋霍尔电流产生的影响。研究活动结合了联合收割机精密纳米光刻，高质量2D材料堆栈的组装，以及低温传输，磁传输和自旋传输测量。

Non-Technical AbstractThis project aims to explore the physics and applications of graphene and bilayer graphene, which consists of one or two layers of carbon atoms arranged in a hexagonal lattice. The arrangement of the carbon atoms leads to unique electronic properties that may become the foundation of a new generation of low-power nanoelectronics and novel types of electronics. These new devices would utilize the electron spin, a quantum mechanical property of electrons, rather than the electron charge, as in conventional electronics. The research activities will prepare graduate students and undergraduate students with advanced technical, methodological and communication skills to contribute to the advancement of nanoscience and nanotechnology in academic or industrial settings. The research team interacts with high-school students (grade 10-12) through a 3-hour workshop combining lecture, demonstration, lab tour and hands-on activities to introduce the properties and applications of atomically thin materials. The workshop is offered to participants through partnership with the Penn State Science U Leadership Summer Camp and the Upward Bound (UB) and Upward Bound Migrant (UBM) programs, which specially target students from low-achieving PA school districts. Technical AbstractSpin, valley, layer and their intimate couplings are distinguishing characteristics of hexagonal 2D crystals, the exploitation of which can lead to new fundamental insights as well as potential applications. The research activities include two thrusts that aim to control the valley degree of freedom in bilayer graphene nanostructures and engineer local spin-orbit coupling in graphene respectively. The first thrust employs dual split-gated devices to study the exotic properties of a new 1D edge mode (kink state) arising at the line junction of two oppositely biased bilayer graphene. Studies of the kink state in the presence of a magnetic field and superconducting electrodes illuminate its interplay with quantum Hall magnetism and proximal superconductivity. The second thrust utilizes adatom functionalization, in particular fluorination, to engineer local spin-orbit coupling in graphene and investigates its impact on spin transport and spin Hall current generation. The research activities combine precision nanolithography, assembly of high-quality 2D material stacks, and low-temperature transport, magneto-transport and spin transport measurements.