CAREER: Electrical Control of Topological Phases in Layered Semimetals

该项目由CMP计划和既定计划共同资助，以刺激竞争研究（EPSCoR）。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，为一类新型材料——拓扑量子材料奠定了基础。这些材料中的电子表现得像粒子，因此可以在固态材料的桌面实验中探索高能物理。这些材料已经导致了对物理学重要主题的更深入的了解，并显示出具有技术应用前景的新颖电子特性的万花筒，例如非常高的迁移率甚至节能设备的无耗散传输。操纵这些特性的能力，特别是使用电气方法来打开和关闭，增强或抑制，有望实现新一代技术。本项目旨在培养这种能力，为在技术应用中实现这些新材料提供见解。将广泛的教育和推广工作整合到研究活动中，以准备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。与历史上的黑人学院或大学以及代表性不足的当地社区合作，以增加研究和教育机会。技术摘要：本课题通过层状拓扑半金属的工程晶格和时间反转对称性来研究拓扑电子态的电气控制。拓扑相位控制是通过静电电子和空穴掺杂和电化学嵌入在全固体双电层器件中实现的，这是基于电子密度作为一个调节旋钮来改变这些对称性并驱动拓扑相变的假设。本研究旨在研究狄拉克节线半金属、拓扑绝缘体、正常绝缘体和Weyl半金属相之间的拓扑相变。所获得的知识和开发的技术进一步使拓扑相的空间选择性控制能够形成横向异质结构，从而为探索令人兴奋的量子物理提供了一个多功能平台。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的新型受限诱导现象创造根本的新见解。最后，教育计划紧密结合，并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，从长远来看，继续有利于凝聚态物质和材料科学研究。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。

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.