CAREER: Two-dimensional Van Der Waals systems with tunable spin-orbit coupling

该职业奖支持理论研究和教育，以调查由堆叠的二维层制成的新型材料的特性，其中电子相互作用的方式以及与晶格的相互作用，以及材料缺陷的作用可以通过实验来控制和调整。这项研究的动机是最近的实验突破，这些突破表明，单原子厚度的不同材料层可以被隔离，然后堆叠形成新的系统，“范德华斯系统”，其中不同的层通过弱静电相互作用结合在一起，以荷兰诺贝尔奖获得者约翰内斯·迪德里克·范德华斯命名。范德华体系的性质可以通过选择形成结构的材料和堆叠顺序来设计和调整到前所未有的程度。特别有趣的是自旋轨道相互作用。电子有一种叫做自旋的固有特性，它看起来就像一个小陀螺。电子的自旋也与其固有的磁性有关；它的行为就像一个小条形磁铁。当电子在材料中移动时，它将经历晶格中原子核心的磁场，这是相对论的结果。PI将研究可调自旋轨道相互作用和晶体缺陷对电子平衡状态的影响，以及电荷和自旋在范德华体系中的移动方式。杂质通常被认为是一种妨害，会破坏清洁系统的特性。然而，杂质对于获得理想的物理效果是必不可少的，并且可以用作宿主系统基态的独特原子尺度探针。PI计划研究范德华体系中杂质诱导的状态，并探索在这些材料中使用无序来实现新功能的可能性。该奖项支持的教育活动包括设计和开发便携式工具包，为K-12学生进行演示。“公文包里的物理”将被用于经济条件较差的学校。PI还将开发一门针对高级本科生和一至二年级研究生的凝聚态物理新课程，并根据学生的贡献制作多媒体“维基教科书”，向学生和公众展示和传播课程材料。该职业奖支持理论研究和教育，以调查新实现的范德华材料中自旋轨道耦合，电子-电子相互作用和无序之间的相互作用。这些材料的自旋轨道耦合、相互作用和无序强度可以通过改变实验可控量来调节。PI计划研究：(i)可调谐自旋轨道耦合对相关态的影响；（ii）无序的类型和强度如何影响基态，并研究在不同破对称态之间实现无序调谐相变的可能性；（iii）可调谐自旋轨道耦合对杂质束缚态性质的影响；（iv）异常耦合电荷-自旋输运和电流驱动的自旋力矩，以及如何通过调整自旋-轨道耦合来改变它们。为了开展这项调查，PI将使用场论、图解和计算方法的结合。特别是，基于PI开发的功能方法的计算方法将用于研究相关长度大于电子费米波长的无序存在。理论描述将通过与实验小组的密切合作得到验证和完善。通过研究具有可调谐自旋-轨道耦合、相互作用和无序的范德华系统，所提出的研究将提供超越范德华系统领域的理论结果，并与电子系统中自旋-轨道耦合效应的广泛主题直接相关。该奖项支持的教育活动包括设计和开发便携式工具包，为K-12学生进行演示。“公文包里的物理”将被用于经济条件较差的学校。PI还将开发一门针对高级本科生和一至二年级研究生的凝聚态物理新课程，并根据学生的贡献制作多媒体“维基教科书”，向学生和公众展示和传播课程材料。

NONTECHNICAL SUMMARYThis CAREER award supports theoretical research and education to investigate the properties of novel materials made of stacked two-dimensional layers in which the way electrons interact with each other and with the crystal lattice, and the role of materials defects can be controlled and tuned experimentally. This research is motivated by recent experimental breakthroughs that have demonstrated that single, one-atom thick, layers of different materials can be isolated and then stacked to form novel systems, "van der Waals systems", in which the different layers are held together by a weak electrostatic interaction named after the Dutch Nobel prize winner Johannes Diderik van der Waals.The properties of van der Waals systems can be engineered and tuned to an unprecedented degree by selecting the materials forming the structure, and the stacking order. Of particular interest is the spin-orbit interaction. Electrons have an intrinsic property called spin where it appears as if the electron spins like a tiny top. The spin of the electron is also connected to its intrinsic magnetic properties; it behaves as though it was a tiny bar magnet. As an electron moves through a material it will experience a magnetic field from the atomic cores in the lattice as a consequence of the theory of relativity. The PI will investigate the effect of tunable spin-orbit interactions and crystalline imperfections on the equilibrium state of the electrons and on the way charge and spin move through van der Waals systems. Impurities are often regarded as a nuisance that spoils the properties of a clean system. However, impurities can be essential to obtain desirable physical effects and can be used as unique atomic-scale probes of the ground state of the host system. The PI plans to study impurity-induced states in van der Waals systems and to explore the possibility to use disorder to achieve novel functionalities in these materials.The educational activities supported by this award include the design and development of a portable kit to carry out demonstrations for K-12 students. This Physics in a Briefcase will be used to reach economically disadvantaged schools. The PI will also develop a new course on condensed matter physics tailored to advanced undergraduate and 1st-2nd year graduate students, and a multimedia "wikibook" created from students' contributions to present and disseminate course material to students and the public.TECHNICAL SUMMARYThis CAREER award supports theoretical research and education to investigate the interplay between spin-orbit coupling, electron-electron interactions, and disorder, in newly realized van der Waals materials. The spin-orbit coupling, interactions, and disorder strength can be tuned in these materials by varying experimentally controllable quantities. The PI plans to study: (i) the effect of tunable spin-orbit coupling on correlated states; (ii) how the type and strength of disorder affects the ground state and investigate the possibility to realize disorder-tuned phase transitions between different broken-symmetry states; (iii) the effect of tunable spin-orbit coupling on the properties of impurity bound states; (iv) anomalous coupled charge-spin transport and current-driven spin torques and how they can be modified by tuning the spin-orbit coupling. To carry out this investigation the PI will use a combination of field-theoretic, diagrammatic, and computational approaches. In particular, computational methods based on a functional approach developed by the PI will be used to study the presence of disorder with a correlation length larger than the Fermi wavelength of the electrons. The theoretical description will be verified and refined via close collaboration with experimental groups.By studying van der Waals systems with tunable spin-orbit coupling, interactions, and disorder, the proposed research will provide theoretical results that will transcend the field of van der Waals systems and be directly relevant to the broad topic of the effect of spin-orbit coupling in electronic systems.The educational activities supported by this award include the design and development of a portable kit to carry out demonstrations for K-12 students. This Physics in a Briefcase will be used to reach economically disadvantaged schools. The PI will also develop a new course on condensed matter physics tailored to advanced undergraduate and 1st-2nd year graduate students, and a multimedia "wikibook" created from students' contributions to present and disseminate course material to students and the public.