CAREER: Quantum Transport and Optoelectronics with Helical Crystals

材料的物理性质，以及这些材料如何为社会服务，取决于组成材料的元素以及每个元素在材料结构中的排列方式。 当元素硒或碲结合在一起形成晶体时，元素的排列是相当独特的：原子形成微小的螺旋链，沿着同一方向运行，许多平行链弱结合在一起形成晶体。 鉴于这种不寻常的结构，许多新的物理性质可能会出现也就不足为奇了。 研究小组合成了这些材料，并将它们整合到电子设备中，以创造、控制和探测这些不寻常的特性。 例如，当电子沿着螺旋链运动时，它们预计会产生一个大磁场，这对信息存储和处理很有用。 作为另一个例子，拉伸螺旋有望将这些材料从半导体转变为一种特殊类型的金属，其中出现了新的和有用的量子力学特性。 这项活动被纳入广泛的教育和社区建设工作，旨在培训学生进入量子科学和技术劳动力，向公众传播物理学，并鼓励年轻学生，特别是那些来自代表性不足的群体，选择科学和工程职业。技术摘要：拓扑能带理论彻底改变了人们对凝聚态中可能存在的量子态的理解，这种理解导致了许多这些状态的实验实现，包括各种类型的拓扑绝缘体和狄拉克，外尔和马约拉纳费米子。虽然这些量子态已经被研究了很多年，但基于量子材料的设备的开发仍然处于起步阶段，特别是对于Weyl和Majorana系统。这样的设备可以控制、优化、利用和进一步探测这些状态中的一些，以及创建新的状态。该项目汇集了材料合成，二维材料异质结构和量子器件制造/测量，以重新审视两种材料，元素硒和碲，并以量子材料的新视角对其进行探测。我们的目标是实验回答这些材料的性质和能力的基本问题，跨越广泛的主题：动力磁电效应;费米能量调谐，应变修改，和限制的缺口外尔材料;和碲和层状超导体的异质结构作为一个潜在的马约拉纳平台。 这些问题的答案有可能建立三角Se和Te作为首要的量子材料，影响广泛的基础和应用主题，包括自旋电子学，谷电子学，拓扑（半）金属，太阳能收集，和（拓扑学）该奖项反映了美国国家科学基金会的法定使命，并通过利用基金会的知识价值和更广泛的影响进行评估，被认为值得支持审查标准。

Nontechnical abstract:The physical properties of materials, and consequently how those materials may be put to work for the benefit of society, is dictated by which elements compose the material and how each element is arranged within the structure of the material. When the elements selenium or tellurium bond together to form a crystal, the arrangement of the elements is rather unique: the atoms form tiny spiraling chains running in the same direction with many parallel chains weakly bonded together to create the crystal. Given this unusual structure, it is not surprising that many new physical properties could arise. The research team synthesizes these materials and incorporates them into electronic devices that create, control and probe the unusual properties. For example, as electrons travel along the spiraling chains, they are expected to generate a large magnetic field that could be useful for information storage and processing. As another example, stretching the spirals is expected to transform these materials from a semiconductor into a special type of metal in which new and useful quantum mechanical properties emerge. This activity is integrated into a broad scope of educational and community-building efforts aimed at training students to enter the quantum science and technology workforce, communicating physics to the general public, and inspiring young students, particularly those from underrepresented groups, to choose careers in science and engineering.Technical abstract:Topological band theory has revolutionized the understanding of what kinds of quantum states are possible in condensed matter settings, and this understanding has led to the experimental realization of many of these states, including various types of topological insulators and Dirac, Weyl, and Majorana fermions. While these quantum states have been investigated with increasing vigor over many years, the development of devices based on quantum materials remains in its infancy, particularly for Weyl and Majorana systems. Such devices could control, optimize, utilize, and further probe some of these states, as well as create new ones. This project converges materials synthesis, two-dimensional material heterostructures, and quantum device fabrication/measurement to revisit two materials, elemental selenium and tellurium, and probe them in a new light as quantum materials. The objective is to experimentally answer fundamental questions about the properties and capabilities of these materials spanning a broad range of topics: the kinetic magneto-electric effect; Fermi energy tuning, strain modification, and confinement of gapped Weyl materials; and heterostructures of tellurium and layered superconductors as a potential Majorana platform. Answers to these questions have the potential to establish trigonal Se and Te as premier quantum materials impacting a wide range of fundamental and applied topics including spintronics, valleytronics, topological (semi)metals, solar energy harvesting, and (topological) quantum information processing.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.