Electron tunneling spectroscopy of the novel pairing state in the 1-1-5 heavy fermions and possible topological Kondo insulator YbB12

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Non-technical Abstract: In this project, two important topics in condensed matter physics are studied using techniques that explore properties of electrons. First, transport of electricity without dissipation in a superconducting state is a fundamental topic addressed here by investigating a wide group of superconductors to determine the mechanism of superconductivity unambiguously. Second, the other half of this project focuses on topological insulators, a novel class of quantum matter harboring protected conducting states at their surfaces. How this novel property emerges is not yet understood when the interactions are strong. To tackle this unsolved problem, this project applies tunneling spectroscopy to multiple candidate materials in different forms and under hydrostatic pressure. Younger generation of scientists including graduate and undergraduate students are actively involved in this project by undertaking key experimental activities and trained to acquire professional skills such as written and verbal dissemination of their work. Outreach to underrepresented group is planned, as well as engagement in various activities focusing on elevating general public’s literacy in STEM fields.Technical Abstract: This project involves two forefront research topics in condensed matter physics: the pairing mechanism in the 1-1-5 family of heavy-fermion superconductors and the interplay between strong correlations and topology in correlated topological materials. Electron tunneling spectroscopy is employed to reveal their key spectroscopic properties that are essential for microscopic understanding of the underlying physics. Despite the widely accepted pairing mechanism involving spin fluctuations in heavy-fermion superconductors, key experimental signatures for the 1-1-5 family of heavy fermions remain controversial/missing. The resultant spectroscopic information is expected to lead to a deepened understanding of the interplay between strong correlations and topology. Younger generation of scientists including graduate and undergraduate students are actively involved in this project by undertaking key experimental activities and trained for acquiring professional skills such as written and verbal dissemination of their work. All personnel involved in this project participate in outreach activities to elevate general public’s literacy in STEM fields.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.