CAREER:Beyond Ideal Quantum Materials: Understanding the Critical Role of Disorder and Electron-Electron Interactions

功能量子材料，如高温超导体、巨磁阻材料和稀磁半导体，是凝聚态物理研究的前沿。人们正在积极探索这些材料的变革性技术应用，包括高效的能源产生、储存和传输。理解这些量子材料中出现的奇异物质相背后的基本机制是一个巨大的挑战，必须克服这个挑战才能最大限度地提高技术进步。由于多电子问题的复杂性，解析理论往往变得不可靠，需要进行数值处理。该职业奖支持旨在更好地理解和描述量子材料中的电子定位和相变的计算和理论研究和教育，量子材料的性质由强电子-电子相互作用和无序控制。到目前为止，大多数关于这类量子材料的理论和计算研究都是在理想化的系统上进行的，通常是基于过于简化的玩具模型，这些模型没有考虑到真实材料的内在复杂性。要理解新发现的量子材料中物质的奇异相，需要的不仅仅是这样的简化。这项研究将扩展现有的数值工具，以面对材料的复杂性，并使深入研究量子系统中的电子局域化和相变成为可能。这个项目的一个重要组成部分是为K-12和大学生的不同群体提供教育和推广。这一努力的目标是通过整合研究和教育，培养一支多样化和有竞争力的量子智能劳动力队伍。这一目标将通过：1)培养研究生和本科生的研究和高性能计算；2)开设创新的本科材料物理课程，重点介绍凝聚态物理和计算的最新进展；3)为研究生举办计算机工作坊；4)为女性和其他在物理领域未被充分代表的群体提供指导和外展活动，并有针对性地吸引初中和高中阶段的年轻女性。该职业奖支持研究和教育，重点是具有强电子-电子相互作用和无序的功能量子材料的理论和计算研究。我们目前对相关电子量子材料的大部分知识都是建立在理想化和简化玩具模型的研究基础上的，这些模型没有考虑到真实系统的内在复杂性。提出的研究的总体目标是通过对量子材料进行超越理想模型的研究，通过包含无序，多轨道结构和远程库仑相互作用来增强对量子材料的理解。研究团队将开发新的理论方法和多体数值工具，以扩展现有蒙特卡罗和量子簇嵌入方法的能力。具体来说，研究将集中在最近实验发现背景下出现的二维电子系统中的电子局部化和金属-绝缘体跃迁的几个基本开放问题上。例如：1)通过系统研究非局域相关和远程电子-电子相互作用的影响，确定二维电子系统中Mott金属-绝缘体跃迁的命运；2)研究单带和多轨道系统中Mott金属-绝缘体跃迁附近的无序、电子-电子相互作用和量子临界之间的相互作用；3)利用基于ab-initio的有效哈密顿方法，利用无序来定位中间带半导体和拓扑绝缘体中的电子。教育和推广部分的目标是通过整合研究和教育，培养一支多样化和有竞争力的量子智能劳动力队伍。这一目标将通过几个组成部分来实现：1)设计一个创新的量子材料本科材料科学课程，重点是凝聚态物理和计算的最新进展；2)为研究生举办关于强相互作用和无序系统的现代量子多体数值技术的计算研讨会；3)培养量子材料研究和高性能计算方面的本科生和研究生。建议的外联工作重点是指导和鼓励妇女和其他在科学学科中代表性不足的群体参与PI成立的妇女参与物理学小组。PI将为初高中学生组织各种外联物理示范讲习班，以及网络和专业发展指导活动。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 SUMMARYFunctional quantum materials, such as high temperature superconductors, colossal magnetoresistance materials, and dilute magnetic semiconductors, are at the forefront of condensed matter physics research. These materials are being actively explored for transformative technological applications, including efficient energy generation, storage, and transmission. Understanding the fundamental mechanisms behind the exotic phases of matter emerging in these quantum materials is a grand challenge, which must be overcome to maximize technological advancement. Due to the complexity of the many-electron problem, analytic theories often become unreliable, and numerical treatment is required. This CAREER award supports computational and theoretical research and education aimed at better understanding and description of electron localization and phase transitions in quantum materials, properties of which are governed by strong electron-electron interactions and disorder. So far, most of the theoretical and computational research on such quantum materials has been performed on idealized systems, often based on overly simplified toy models, which do not take into account the intrinsic complexity of real materials. Understanding exotic phases of matter in newly discovered quantum materials requires going beyond such simplifications. This research will extend the existing numerical tools to confront material complexity and enable in-depth study of electron localization and phase transitions in quantum systems. An important component of this project is education and outreach for a diverse body of K-12 and college students. The goal of this effort is to develop a diverse and competitive quantum smart workforce by integrating research and education. This goal will be met through: 1) training graduate and undergraduate students in research and high-performance computing; 2) developing an innovative undergraduate material physics course with an emphasis on recent advances in condensed matter physics and computation; 3) conducting computational workshop for graduate students; 4) providing mentoring and outreach activities for women and other groups underrepresented in physics, and targeted outreach to engage young women at the middle- and high-school levels.TECHNICAL SUMMARYThis CAREER award supports research and education that focuses on theoretical and computational study of functional quantum materials with strong electron-electron interactions and disorder. Much of our present knowledge of correlated electron quantum materials is built on studies performed for idealized and simplified toy models that do not take into account the intrinsic complexity of real systems. The overarching goal of the proposed research is to enhance understanding of quantum materials by conducting studies of quantum materials beyond ideal models, via the inclusion of disorder, multi-orbital structure, and long-range Coulomb interactions. The research team will develop new theoretical approaches and many-body numerical tools that will extend the capabilities of the existing Monte Carlo and quantum cluster embedding methods. Specifically, the research will focus on several fundamental open questions of electron localization and metal-insulator transition in two-dimensional electron systems that have emerged in the context of recent experimental discoveries. Examples include: 1) determining the fate of Mott metal-insulator transition in two-dimensional electron systems by systematically studying the effect of non-local correlations and long-range electron-electron interactions; 2) investigating the interplay between disorder, electron-electron interactions, and quantum criticality near the Mott metal-insulator transition in single band and multi-orbital systems; 3) exploiting disorder to localize electrons in intermediate band semiconductors and topological insulators using ab-initio based effective Hamiltonian methods.The goal of the educational and outreach components is to develop a diverse and competitive quantum smart workforce by integrating research and education. This goal will be met through several components: 1) designing an innovative quantum material undergraduate material science course with the emphasis on recent advances in condensed matter physics and computation; 2) conducting computational workshops for graduate students on the modern quantum many-body numerical techniques for strongly interacting and disordered systems; 3) training undergraduate and graduate students in quantum material research and high-performance computing. A strong emphasis of the proposed outreach is targeted towards mentoring and encouragement of participation of women and other group underrepresented in scientific disciplines by the PI’s established Women in Physics Group. The PI will organize various outreach physics demonstration workshops for middle and high school students as well as networking and professional development mentoring events.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.