CAREER: Electrical Control of Topological Phases in Layered Semimetals

该项目由CMP计划和已建立的激励竞争研究计划(EPSCoR)联合资助。非技术摘要：拓扑相和相变理论是2016年诺贝尔物理学奖的开创性工作，它为一类新的材料奠定了基础，称为拓扑量子材料。这些材料中的电子行为像粒子，因此能够在固态材料的桌面实验中探索高能物理。这些材料使人们对物理学中的重要课题有了更深入的了解，并展示了新的电子性能的万花筒，具有巨大的技术应用前景，例如非常高的迁移率，甚至是节能设备的无耗散运输。操纵这些特性的能力，特别是使用电气方法来开关、增强或抑制的能力，预计将使新一代技术成为可能。该项目旨在发展这种能力，为在技术应用中实施这些新材料提供见解。在研究活动中纳入了广泛的教育和外联努力，以培养一支多才多艺和多样化的量子材料劳动力队伍，包括实施可扩展的方法来培训具有包容性的不同水平的学生群体，创建跨学科课程以加强材料科学教育并为学生的职业道路做好准备，以及与历史上一直是黑人的学院或大学和当地代表性不足的社区合作以增加研究和教育机会。技术摘要：该项目利用分层拓扑半金属中的工程晶格和时间反转对称性来追求对拓扑电子态的电子控制。在全固体电双层器件中，拓扑相控是通过静电电子和空穴掺杂以及电化学插层来实现的，这是基于电子密度作为调谐旋钮来改变这些对称性和驱动拓扑相变的假设。本研究旨在研究Dirac节线半金属、拓扑绝缘体、正常绝缘体和Weyl半金属相之间的拓扑相变。所获得的知识和发展的技术进一步使对拓扑相的空间选择性控制形成横向异质结构，从而为探索令人兴奋的量子物理提供了一个通用的平台。在此基础上，本项目还旨在建立和展示实现完全受限拓扑费米子的具体策略，并为拓扑量子材料中新的受限诱导现象提供全新的见解。最后，教育计划是紧密结合的，通过培训具有广泛量子相关技能的多样化劳动力来利用研究活动，并从长远来看，继续使凝聚态物质和材料科学研究受益。该奖项反映了NSF的法定使命，并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。

This project is jointly funded by CMP Program and by the Established Program to Stimulate Competitive Research (EPSCoR).Non-technical abstract:The theory of topological phases and phase transitions, which is the seminal work of the 2016 Nobel Prize in Physics, establishes the foundation for a novel class of materials, referred as topological quantum materials. Electrons in these materials behaves like particles, thus enabling exploring high energy physics in tabletop experiments on solid state materials. These materials have been leading to deeper knowledge of important topics in physics, and display a kaleidoscope of novel electronic properties with great promise for technology applications, such as very high mobility or even dissipationless transport for energy-saving devices. The ability to manipulate these properties, particularly using electrical approaches to switch on and off, enhancing or suppression, is expected to enable a new generation of technology. This project aims to develop such ability to provide insights to implement those novel materials in technology applications. Integrated into the research activities is a broad scope of educational and outreach efforts to prepare a multi-talented and diverse quantum material workforce, including implementing a scalable approach to train an inclusive group of students of various levels, creating interdisciplinary courses to enhance material science education and prepare students for career paths, and partnering with a historically black college or university and a local underrepresented community to enhance research and education opportunities. Technical abstract:This project pursues the electrical control of topological electronic states by engineering lattice and time reversal symmetries in layered topological semimetals. Topological phase control is performed by electrostatic electron and hole doping and electrochemical intercalation in all-solid electrical double layer devices, which is based on the hypothesis that electron density acts as a tuning knob to modify these symmetries and drive topological phase transitions. This research aims to topological phase transitions between Dirac nodal-line semimetal, topological insulator, normal insulator, and Weyl semimetal phases. The obtained knowledge and developed techniques further enable the spatially selective control of topological phases to form lateral heterostructures, leading to a versatile platform to explore exciting quantum physics. Based on that, this project also targets to establish and demonstrate concrete strategies for realizing completely confined topological fermions and creating fundamentally new insights for novel confinement-induced phenomena in topological quantum materials. Finally, the education plan is closely integrated and leverages the research activities by training a diverse workforce with a broad mix of quantum-related skills, and in the long term, continue to benefit the condensed matter and materials science research.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.