Novel Phenomena in spin orbit coupled systems

该奖项支持理论研究和教育，以研究电子物质在许多身体系统中的新功能。PI将研究材料中涉及大量电子的状态，这些电子是由两种成分的相互作用引起的：1）电子对之间的相互作用，以及2）强自旋轨道相互作用，它量化了电子自旋的影响，这是一种基本的量子力学现象，其中电子看起来像陀螺一样旋转。在过去的十年里，许多新的物质相被理论上提出和实验上发现。在许多情况下，它们的独特特征可以借助数学中处理形状、变形和拓扑的分支的概念来描述。拓扑学、自旋轨道耦合和多体物理学的交叉是一个丰富的和当前的研究领域，可能会导致新的器件技术。PI将重点研究两种特定类型的材料系统。第一类是二维过渡金属二硫属化物。这些材料基本上是单原子层厚，由过渡金属（如元素钨或钼）和硫属元素（如元素硫或硒）制成。这些项目探讨：i）自旋和电子运动的耦合如何导致具有设备应用潜力的新的磁特性; ii）由于相互作用，物质的新磁状态是可能的;以及iii）拓扑结构的后果是否允许使用圆偏振光控制设备特性的新方法。第二种是拓扑半金属，它是金属和半导体之间的中间体。PI将绘制出这些系统中支持的可能的相和现象，并同时使用所学到的经验教训来更好地理解具有强自旋轨道相互作用的材料。研究团队将包括一名研究生，他将接受所需的技术专业知识培训，并对真实的材料进行理解。该奖项将有助于支持加州大学河滨分校的外联工作，为高中教师提供津贴，参加由物理和天文学系主办的为期一周的教师暑期学院。该奖项支持理论研究和教育，以研究电子物质在许多身体系统中的新功能。PI旨在发现和设计新的物质状态和相关性质，这些性质来自多体系统中自旋轨道耦合和相互作用的相互作用。拓扑非平凡态，如拓扑绝缘体和外尔半金属，出现在非相互作用系统中。自然会产生这样的问题：当包含交互时会发生什么？拓扑方面还存在吗？是否实现了允许新功能的新相关阶段？PI将在二维dichalcogenides和三维Weyl半金属的背景下解决这些问题。二维dichalcogenides的项目旨在表征由于自旋轨道耦合提供的独特能带结构而产生的新磁现象。例如，近藤效应的性质，其中杂质自旋被屏蔽的主机电子，将建立。具有自旋特异性的光电耦合为检测和操纵这种关联相提供了一种新的探针，并对其进行了理论分析。非平凡拓扑在自旋电子学中也有潜在的应用，这是由于电子在外电场中获得的反常速度。PI将探索这些新的功能和非局部自旋阀器件的可行性，以及这些现象是否可以在磁绝缘体附近进一步增强。Weyl半金属是拓扑的，但在体中没有能隙。这是由于能带交叉的拓扑保护，并且只有耦合具有相反拓扑电荷的节点的相互作用才能打开间隙。PI将表征激子相及其由于电子-电子库仑排斥而产生的性质。对称性的考虑，场论技术和计算的组合将被用来实现该计划的广泛目标。研究团队将包括一名研究生，他将接受所需的技术专业知识的培训，并在发展对真实的材料的理解。该奖项将有助于支持加州大学河滨分校的外联工作，为高中教师提供津贴，参加由物理和天文学系主办的为期一周的教师暑期学院。

NONTECHNICAL SUMMARYThis award supports theoretical research and education to study new states of electronic matter with novel functionalities in many body systems. The PI will investigate states involving a large number of electrons in materials that arise from the interplay of two ingredients: 1) the interaction between pairs of electrons, and 2) strong spin-orbit interaction which quantifies the influence of an electron's spin, a fundamentally quantum mechanical phenomenon in which an electron appears to spin like a top, on its motion. Over the last decade a number of new phases of matter have been theoretically proposed and experimentally discovered. In many cases, their unique characteristics can be described with the help of concepts from the branch of mathematics dealing with shape, deformation and topology. The intersection of topology, spin-orbit coupling and many body physics is a rich and current area of study that may lead to new device technologies.The PI will focus investigation on two specific kinds of materials systems. The first kind is comprised of the two-dimensional transition metal dichalcogenides. These are materials that are essentially a single atomic layer thick, made from a transition metal such as the elements Tungsten or Molybdenum, and a chalcogen such as the elements Sulphur or Selenium. The projects explore: i) how the coupling of spin and electron motion can lead to new magnetic properties with the potential for device applications; ii) what new magnetic states of matter are possible due to the interactions; and iii) whether consequences of topology allow for new ways of controlling device characteristics using circularly polarized light. The second kind is comprised of the topological semimetals, which are intermediate between a metal and a semiconductor. The PI will map out the possible phases and phenomena supported in these systems, and in parallel use the lessons learned to develop a better understanding of materials with strong spin-orbit interactions.The research team will include one graduate student who will be trained in the needed technical expertise, and in developing an understanding of real materials. The award will help support an outreach effort at University of California-Riverside, by providing stipends for high school teachers to attend a week long Summer Academy for Teachers hosted by the Physics and Astronomy department. TECHNICAL SUMMARYThis award supports theoretical research and education to study new states of electronic matter with novel functionalities in many body systems. The PI aims to discover and design new states of matter and associated properties arising from the interplay of spin-orbit coupling and interactions in many-body systems. Topologically nontrivial states such as topological insulators and Weyl semimetals arise in non-interacting systems. Natural questions that arise are: What happens when interactions are included? Do the topological aspects survive? Are new correlated phases realized which allow new functionalities? The PI will address these questions in the context of two-dimensional dichalcogenides and three-dimensional Weyl semimetals.The projects on two dimensional dichalcogenides aim to characterize new magnetic phenomena that arise due to unique band structure afforded by spin-orbit coupling. For example the nature of the Kondo effect, where an impurity spin is screened by the host electrons, will be established. Opto-electronic coupling with spin specificity provides a new probe to test and manipulate this correlated phase which will be theoretically analyzed. Nontrivial topology also has potential application in spintronics due to the anomalous velocity acquired by the electrons in external electric fields. The PI will explore these new functionalities and the viability of a nonlocal spin-valve device, and whether these phenomena can be further enhanced in proximity to a magnetic insulator.Weyl semimetals are topological yet possess no energy gap in the bulk. This is due to the topological protection of the band crossings and only interactions that couple nodes with opposite topological charge can open a gap. The PI will characterize the excitonic phases and their properties that arise due to electron-electron Coulomb repulsion. A combination of symmetry considerations, field theoretic techniques, and computation will be utilized to achieve the broad objectives of the program.The research team will include one graduate student who will be trained in the needed technical expertise, and in developing an understanding of real materials. The award will help support an outreach effort at University of California-Riverside, by providing stipends for high school teachers to attend a week long Summer Academy for Teachers hosted by the Physics and Astronomy department.