Fermi Surface Topology and the Superconducting Proximity Effect

Boston College, Chestnut Hill MA

Investigators

Abstract

Non-Technical Abstract: Unconventional superconductivity and the conditions under which associated physical phenomena may be observed have remained one of the most active areas of condensed matter physics. This search, began nearly 60 years ago with Meissner's original discovery of the proximity effect (induction of superconductivity into a normal material via direct contact). Interest in the proximity effect was reinvigorated by predictions of new phases and their associated particles (non-abelian anyons) that can be used for next generation topological quantum computing. The PI was the first to demonstrate a proximity effect between a high Tc, unconventional superconductor (cuprates) and a semiconductor. Building on recent success with a range of superconductors, the PI pursues the emergence of new superconducting states. Specific focus is on the role of the electronic configuration of both materials in generating proximity effects and developing new methods to probe the interface and emergent particles. Emphasis is given to diversification of the STEM workforce, including informing K-12 about 2D materials and topology via the Lynch School of Education's "Science Educators for Urban Schools" program; creating hands-on demonstrations for BC's Making Science a Fan-Tastic Experience, increasing participation of women, first generation and underrepresented minorities by partnering with BC's McNair, National Research Mentoring Network and Women in Science and Technology programs. Technical Abstract: The proposal aims to understand the role of the Fermi surface of the normal and superconducting materials in the proximity effect. It is based on the success of the PI's mechanical bonding technique in generating a proximity effect between various superconductors and Dirac materials. The PI pursues the emergence of new unconventional/topological superconducting states. Coordinated fabrication and spectroscopic efforts provide answers to several questions in the field of proximity induced topological superconductivity: What is the role of the superconductor's Fermi surface? Does proximity induced superconductivity emerge in Weyl semimetals? Is the resulting superconductivity unconventional? Can we detect and manipulate the bound states that emerge at edges? Bound states and the proximity effect are explored as the superconductor's Fermi surface is tuned in FeTe1-xSex. Next the proximity effect are searched for in the WSM, MoTe2. The last stages employs spectroscopic probes to uncover the unconventional/topological nature of the superconductivity, along with the resulting excitations.