CAREER: Structural Control of Spin-Orbit Coupling

非技术总结该奖项支持理论和计算研究和教育活动，旨在从根本上了解固体晶体材料中电子的轨道和自旋自由度之间的相互作用，称为自旋-轨道耦合。虽然每个原子，因此每个材料都有一些自旋-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利的。这些应用包括自旋晶体管，它能够控制电子的自旋电流。如果实现了商业规模，自旋晶体管可能会在电子行业引发一场自旋电子学革命。PI和他的团队将利用计算机模拟和被称为群论的数学领域来了解晶体结构如何被外部操纵以诱导不同的自旋轨道效应。这一基本认识有望导致对新材料的预测，这些新材料可能有助于实现商业规模的自旋电子学技术。除了研究工作，该奖项还支持对研究生和本科生的培训和教育，以及开发与晶体结构相关概念的新教学方法。这一新方法将利用3D打印机的广泛和低成本可获得性，这种打印机将被用来制造有利于本科生和研究生学习的模型。这些模型的计算机文件将与学生的一套随附练习一起公开分发。该奖项支持研究和教育活动，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性的联系的基本理解。其中包括众所周知的拉什巴和德雷塞尔豪斯效应，以及电子哈密顿中的许多高阶项。虽然有许多自旋电子学装置的提议利用了自旋-轨道耦合，但在模型哈密顿量和实际材料之间存在差距，在这些材料中，期望的自旋-轨道效应通常很小，或者哈密顿量具有使观察到的现象复杂化的更高阶项。该奖项旨在通过结合第一性原理计算(密度泛函理论和动力平均场理论)和群论提取具有材料特定参数的现实模型来填补这一空白。基团表象将被用来阐明晶体结构扭曲和电子结构之间的耦合，并将发现实现自旋相关电子结构的电场控制的新方法以及实现这些方法的材料。此外，还将用第一性原理关联电子方法研究强关联过渡金属氧化物晶体结构和声子谱中强自旋轨道耦合的影响。除了支持博士生的教育外，该奖项还为开发教材提供支持，以便向材料科学、物理和化学学生更有效地教授结晶学概念。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教授对称性相关概念的工具。这将通过使用商业上可用的用于添加剂制造的设置来实现。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，可以通过广泛可用的3D打印机以低成本生产。该图书馆将与一系列配套活动一起向公众开放。该奖项反映了NSF的法定使命，并已通过使用基金会的智力优势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.