Ultrasensitive Magneto-optic Imaging of Correlated Phases in Topological Materials

非技术摘要：未来的量子计算机和量子设备很可能基于通过其固有特性保护其免受噪音影响的材料，从而使这些设备的操作对环境扰动具有很强的抵抗力。然而，这些复杂材料及其物相的基本物理性质才刚刚开始揭示。研究小组专注于两个这样的阶段：在超导体和磁性拓扑绝缘体之间的交界处发现的手性边缘状态，以及在略微磁化的拓扑近藤绝缘体表面发现的手性边缘状态，这两个阶段都有望构建强大的量子计算机。在这个项目中，PI和他的团队使用了一系列实验工具，包括精确的磁光成像来研究这两个手性边缘状态。这些结果可以为可能在室温下工作的拓扑保护信息处理提供知识库。科学和教育部分为研究生和本科生提供综合和严格的科学培训，包括来自代表性不足群体的学生。通过一个外展项目，可以将科学的兴奋传递给少数民族和女中学生。技术摘要：手征边态是一种复杂的拓扑结构，在量子器件中具有潜在的应用价值。然而，它们的大部分物理特性仍不为人所知。在这个项目中，PI和研究小组利用他们小组中新开发的MK-Sagnac干涉仪显微镜来成像和研究两种这样的拓扑结构：超导体/QAH结中的量子反常霍尔态及其相关的Majorana手征模，以及拓扑Kondo绝缘体SmB6表面的磁手性边态。由于表面和块状物质在拓扑材料中通常具有截然不同的物理性质，在这个项目中，研究团队同时进行Sagnac、扭矩磁测量和传输测量，以清楚地区分从块状和表面态到前所未有的低温的贡献。这些测量可以解决QAH态、手性Majorana边缘模和SmB6表面磁结构的边缘态和体态上复杂的自旋和磁化结构。这个项目可能解决拓扑材料和器件领域中的重要问题：1.我们能在接近环境温度的温度下稳定QAH效应以用于实际器件应用吗？2.手性Majorana边缘模的自旋结构是什么？3.在拓扑近藤绝缘体的表面态中发现的量子化电导的性质是什么？科学和教育部分为研究生和本科生提供综合和严格的科学培训，包括来自代表性不足群体的学生。通过一个推广计划，科学的兴奋可以传达给少数民族和女中学生。这个奖项反映了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。

Nontechnical Abstract: Future quantum computers and quantum devices will likely be based on materials that are protected from noise by their intrinsic features, making the operation of these devices robust against environmental perturbations. The fundamental physical nature of these complex materials and their phases, however, is just starting to be revealed. The research team focuses on two such phases: the chiral edge states found in the junction between a superconductor and a magnetic topological insulator, and on the surface of a slightly magnetized topological Kondo insulator, both holding promise for constructing robust quantum computers. In this project, the PI and his team use a set of experimental tools including precision magneto-optic imaging to investigate these two chiral edge states. The results could provide a knowledge base for topologically protected information processing, potentially operating at room temperature. The science and education components provide integrated and rigorous scientific training for graduate and undergraduate students, so including students from underrepresented groups. Through an outreach program, the excitement of science could be conveyed to minority and female middle school students. Technical Abstract: Chiral edge states are intricate topological structures that are potentially useful for quantum devices. However, much of their physics remains unknown. In this project, the PI and the research team utilize a newly developed mK-Sagnac interferometer-microscope in their group to image and investigate two such topological structures: the quantum anomalous Hall (QAH) state and the related Majorana chiral modes in a superconductor/QAH junction, and the magnetic chiral edge states on the surface of the topological Kondo insulator SmB6. As surface and bulk often have distinctively different physics properties in topological materials, in this project, the research team performs simultaneous Sagnac, torque magnetometry, and transport measurements to clearly distinguish the contributions from bulk and surface states down to unprecedented low temperatures. These measurements could resolve the intricate spin and magnetization structures on the edge and bulk states of QAH states, chiral Majorana edge mode, and SmB6 surface magnetic structure. This project can potentially address important questions in the field of topological materials and devices: 1. Can we stabilize QAH effect at temperatures close to ambient temperature for practical device applications? 2. What are the spin structures of the chiral Majorana edge mode? 3. What is the nature of the quantized conductance found in the surface state of topological Kondo insulator? The science and education components provide integrated and rigorous scientific training for graduate and undergraduate students, so including students from underrepresented groups. Through an outreach program, the excitement of science could be conveyed to minority and female middle school students.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.