Topological and Spin Transport Experiments in Narrow Bandgap Materials

* 技术摘要 * 拓扑绝缘体的理论进展蓬勃发展，而由于普遍缺乏表面态主导电导率的高质量晶体，实验工作取得了较为温和的进展。这个计画是一个广泛的努力，借由分子束磊晶来成长锑基半导体，以进行拓扑与自旋研究。该项目将开发量子限制Sb作为新的3D拓扑绝缘体;推进InAs/GaSb复合量子威尔斯的生长以用于2D拓扑绝缘体研究;探索基于InSb量子线和接近超导体的威尔斯的拓扑超导体;并研究自旋干涉和自旋轨道耦合的门控。除了Sb基材料在基础物理学中可能发挥的作用之外，它们的高电子迁移率和小带隙对于电子和光子器件应用也很有意义。由于该项目的重点是晶体生长，它将有助于学生在技术重要性领域就业的准备。该组织在指导女学生方面有着良好的记录，并将继续鼓励K-12学生通过他们的外展活动和促进STEM更大多样性的努力探索科学和工程职业。非技术摘要 * 从历史上看，材料的增长对基础凝聚态物理和技术进步都具有深远的重要性。拓扑绝缘体是最近发现的一类具有无与伦比性能的材料，其理论进展非常活跃。然而，由于缺乏用于电导率和相关输运实验的高质量材料，实验工作取得了较为温和的进展。该项目解决了实验限制，广泛致力于Sb基半导体的拓扑和自旋研究的增长。除了Sb基材料在基础物理学中可能发挥的作用之外，它们的高电子迁移率和小带隙对于器件应用也很有意义。在这个项目中研究的材料将解决与基础科学和应用科学相关的问题。由于该项目的重点是晶体生长，它将有助于学生在技术重要性领域就业的准备。该小组在指导女研究生方面有着良好的记录，并将继续鼓励年轻学生通过他们的外联活动和其他努力探索科学和工程领域的职业生涯，以促进科学的更大多样性。

****Technical Abstract****Theoretical progress on topological insulators has flourished, while experimental work has made more modest progress due to the general lack of high quality crystals in which surface states dominate the conductivity. This project is a broad effort to grow Sb-based semiconductors by molecular beam epitaxy for topological and spin studies. The project will develop quantum confined Sb as a new 3D topological insulator; advance the growth of InAs/GaSb composite quantum wells for 2D topological insulator studies; explore topological superconductors based on InSb quantum wires and wells in proximity to a superconductor; and study spin interference and gate-control of spin-orbit coupling. In addition to the role Sb-based materials may play in fundamental physics, their high electron mobility and small bandgaps are of interest for electronic and photonic device applications. Because the project focuses on crystal growth, it will contribute to the preparation of students for employment in areas of technological importance. The group has an established record of mentoring female students and will continue to encourage K-12 students to explore careers in science and engineering via their outreach activities and efforts to promote greater diversity in STEM.****Non-Technical Abstract****Historically, materials growth has been of profound importance for both fundamental condensed matter physics and technological advancement. Theoretical progress on topological insulators, a recently discovered class of materials with unparalleled properties, has flourished. Experimental work, however, has made more modest strides due to the scarcity of high quality materials for conductivity and related transport experiments. This project addresses the experimental limitation with a broad effort on the growth of Sb-based semiconductors for topological and spin studies. In addition to the role Sb-based materials may play in fundamental physics, their high electron mobility and small bandgaps are of interest for device applications. The materials studied in this project will address issues relevant to both fundamental and applied science. Because the project focuses on crystal growth, it will contribute to the preparation of students for employment in areas of technological importance. The group has an established record of mentoring female graduate students and will continue to encourage younger students to explore careers in science and engineering via their outreach activities and other efforts to promote greater diversity in science.