CAREER: Structural Control of Spin-Orbit Coupling

该奖项支持理论和计算研究和教育活动，旨在发展对固态晶体材料中电子轨道和自旋自由度之间相互作用的基本理解，称为自旋-轨道耦合。虽然每个原子，因此每种材料，都有一些自旋轨道耦合，但某些晶体化合物中原子排列的对称性可能会导致特定类型的自旋轨道效应，这对未来的技术应用是有益的。这些应用包括自旋晶体管，它可以控制电子的自旋电流。如果在商业规模上实现，自旋晶体管可能会导致电子工业的自旋电子学革命。PI和他的团队将利用计算机模拟和一个被称为群论的数学领域，来理解如何通过外部操纵晶体结构来诱导不同的自旋轨道效应。这种基本的理解有望导致对新材料的预测，这些新材料可以帮助实现商业规模的自旋电子学技术。除了研究工作之外，该奖项还支持研究生和本科生的培训和教育，以及与晶体结构相关概念的新教学方法的开发。这种新方法将利用3D打印机的广泛和低成本的可用性，它将被用来制作模型，这将有助于本科生和研究生的学习。这些模型的计算机文件将与一套学生习题一起公开分发。该奖项支持旨在发展对非磁性晶体材料中不同自旋轨道耦合相关效应的起源以及这些效应与空间群对称的联系的基本理解的研究和教育活动。这些包括著名的Rashba和Dresselhaus效应，以及电子哈密顿量中的许多高阶项。虽然有许多利用自旋轨道耦合的自旋电子学器件方案，但模型哈密顿量与实际材料之间存在差距，其中期望的自旋轨道效应通常很小，或者哈密顿量具有高阶项，使观察到的现象复杂化。该奖项旨在通过结合第一性原理计算（密度泛函理论和动态平均场理论）和群论，通过提取具有材料特定参数的现实模型来填补这一空白。利用群表示来阐明晶体结构畸变与电子结构之间的耦合，发现实现自旋相关电子结构的电场控制的新方法和实现这些方法的材料。此外，将利用第一性原理相关电子方法研究强自旋轨道耦合对强相关过渡金属氧化物晶体结构及其声子谱的影响。除了支持博士生的教育外，该奖项还为开发教育材料提供支持，以便更有效地向材料科学，物理和化学学生教授晶体学概念。该奖项的教育部分旨在开发低成本的晶体结构教育模型和用于教授对称相关概念的工具。这将通过使用商业上可用的增材制造装置来实现。在一名本科生的帮助下，PI将开发一个3D对称和结构模型库，这些模型可以用广泛使用的3D打印机以低成本生产。这个库将与一套附带的练习一起公开提供。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

NONTECHNICAL SUMMARYThis award supports theoretical and computational research and education activities that aim to develop fundamental understanding of the interplay between the orbital and spin degrees of freedom of electrons, called the spin-orbit coupling, in solid state crystalline materials. While every atom, and hence every material, has some spin-orbit coupling, the symmetry of the arrangement of atoms in certain crystalline compounds may lead to specific types of spin-orbit effects that are beneficial for future technological applications. These applications include the spin transistor, which enables the control of the spin-current of the electrons. If realized on a commercial scale, the spin transistor could lead to a spintronics revolution in the electronics industry. The PI and his team will utilize computer simulations and a field of mathematics, referred to as the group theory, to understand how the crystal structure can be externally manipulated to induce different spin-orbit effects. This fundamental understanding is expected to lead to the prediction of new materials that could help realize spintronics technologies on a commercial scale. In addition to research efforts, this award also supports the training and education of graduate and undergraduate students and the development of a new teaching approach for concepts related to crystal structures. This new approach will take advantage of the widespread and low cost availability of 3D printers, which will be used to make models that will facilitate learning for undergraduate and graduate students. The computer files for these models will be disseminated publicly along with a set of accompanying exercises for the students. TECHNICAL SUMMARY This award supports research and educational activities that aim to develop fundamental understanding on the origin of different spin-orbit coupling related effects in nonmagnetic crystalline materials and the connection of these effects with the space group symmetry. These include the well-known Rashba and Dresselhaus effects, as well as numerous higher order terms in the electronic Hamiltonians. While there are many spintronics device proposals that take advantage of spin-orbit coupling, there is a gap between the model Hamiltonians and the real materials where the desired spin-orbit effects are often small, or the Hamiltonians have higher order terms that complicate the observed phenomena. This award aims to fill this gap by extracting realistic models with materials specific parameters by a combination of first principles calculations (Density Functional Theory and Dynamical Mean Field Theory) and group theory. Group representations will be utilized to elucidate the coupling between crystal structural distortions and the electronic structure, and novel means to achieve the electric field control of spin-dependent electronic structure and materials that realize these means will be discovered. Additionally, the effect of strong spin-orbit coupling in the crystal structures of strongly correlated transition metal oxides and their phonon spectra will be studied using first principles correlated electron approaches. In addition to supporting the education of a PhD student, the award also provides support for the development of educational materials for more effective teaching of crystallographic concepts to materials science, physics, and chemistry students. The educational part of the award aims to develop low cost educational models of crystal structures and tools for teaching symmetry-related concepts. This will be achieved by using commercially available setups for additive manufacturing. With the help of an undergraduate student, the PI will develop a library of 3D symmetry and structure models, which can be produced at low cost by widely available 3D printers. This library will be made publicly available along with a set of accompanying exercises.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.