Topological and Spin Transport Experiments in Narrow Bandgap Materials

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****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.