Exploring Emergent Magnetic Topological States in Three-Dimensional Magnetic Topological Insulator Multilayers

非技术摘要基于量子的技术有望在计算、传感、通信和计量学方面取得革命性的进步，但成功取决于创造一个物质平台，在这个平台中，量子状态可以对环境退相干具有健壮性，同时还可以进行控制和测量。一种吸引人的量子技术方案涉及一种称为磁性拓扑绝缘体的材料，在这种材料中，导电电子可以被限制在样品的边缘或表面，并且没有阻力地流动。在这个项目中，基于乐高的设计方案，研究小组使用磁性拓扑绝缘体作为主要的构建块来构建一些多层异质结构，并探索其中的量子涌现现象。这个项目的成功将促进人们对磁学和拓扑学之间相互作用的认识。此外，这项研究加强了宾夕法尼亚州立大学的物质努力。该研究小组积极将研究生和本科生教育整合到该项目中，特别关注于增加未被充分代表的少数族裔的参与，并开发了针对州立大学地区学区的K-12学生和教师的推广活动。技术摘要目前对磁性拓扑态的研究集中在量子反常霍尔态和磁性Weyl半金属。由于缺乏合适的磁性材料平台，其他磁性拓扑相的实现仍然受到限制，包括轴子绝缘体、三维量子反常霍尔态和高阶磁性拓扑绝缘体。这个项目的目标是使用磁性掺杂和非掺杂的拓扑绝缘体和普通绝缘层作为构建块来构建多层异质结构，作为一个高度可调的平台来创建和操纵这些磁性拓扑态。通过结合先进的实验探针，如电输运、扫描隧道显微镜和光谱学，以及角度分辨光电子能谱，结合复杂的理论建模和材料模拟，探索了这些磁性拓扑绝缘体多层异质结构的物理性质。在磁性拓扑绝缘体多层异质结构中实现磁性拓扑态，可能为高能效的电子器件和自旋电子器件铺平道路。这项研究还为量子反常霍尔和轴子绝缘体在量子信息技术中实现变革性的电磁应用提供了科学基础。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。

Non-technical abstractQuantum-based technologies promise revolutionary advances in computing, sensing, communication, and metrology, but success hinges on the creation of a material platform in which a quantum state can be made robust against environmental decoherence yet simultaneously be amendable to control and measurement. An attractive scheme towards quantum-based technologies involves a class of materials called magnetic topological insulators where the conducting electrons can be confined to the edges or surfaces of the sample and flow without resistance. In this project, based on a LEGO design scheme, the research team employs magnetic topological insulators as primary building blocks to construct a number of multilayer heterostructures and explores the emergent quantum phenomena therein. The success of this project will advance knowledge of the interplay between magnetism and topology. Moreover, this research enhances the material efforts at Penn State. This research team actively integrates graduate and undergraduate education into the project, with a particular focus on increasing participation among underrepresented minorities, and also develops outreach activities that target K-12 students and teachers from the State College Area School District.Technical AbstractCurrent research on magnetic topological states focuses on the quantum anomalous Hall state and magnetic Weyl semimetals. The realization of other magnetic topological phases, including axion insulators, the three-dimensional quantum anomalous Hall state, and higher-order magnetic topological insulators, is still limited due to the lack of suitable magnetic material platforms. The goal of this project is to use magnetically doped and undoped topological insulators and normal insulator layers as building blocks to construct multilayer heterostructures as a highly tunable platform for creating and manipulating these magnetic topological states. The physical properties of these magnetic topological insulator multilayer heterostructures are explored by combining advanced experimental probes, such as electrical transport, scanning tunneling microscopy and spectroscopy, and angle-resolved photoemission spectroscopy, with sophisticated theoretical modeling and material simulations. The realization of magnetic topological states in magnetic topological insulator multilayer heterostructures may pave the way for energy-efficient electronic and spintronic devices. This study also provides the scientific foundation in quantum anomalous Hall and axion insulators to achieve transformative electromagnetic applications in quantum information technology.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.