NSF-BSF: Development and Study of Lattice-Derived Flat Band States

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Non-Technical Abstract:While the electronic properties of many conventional metals can be understood as arising from the properties of isolated, charge-carrying electrons, several of the most fundamentally interesting and potentially technologically transformative materials are beyond this paradigm. Such so-called correlated electron materials can host emergent quantum properties such as high temperature superconductivity that are beyond basic predictive paradigms. To find and develop new correlated materials, one recently revisited design principle is the creation of weakly dispersing (flat) electron energy bands. Electrons in such bands are strongly influenced by each other and can offer a natural platform for electronic correlation. This project aims to build on recent progress in this research area to target, synthesize, and study specific materials designed to have strong interaction effects based on flat electronic bands. The broader impacts of the present research program include (1) Potential impact on society through fundamental science innovations including new platforms for quantum technology based on flatband superconductors and new spin liquid materials; (2) Education of the public in topics in quantum science and quantum technology through public engagement with lectures, visualizations, and online content; (3) Engagement of URM students targeted at HBCUs via undergraduate research projects; (4) Increasing the competitive advantage of the USA with partnership of this project with unique capabilities for condensed matter physics at the Weizmann Institute of Science.Technical Abstract:Material systems which can host flat electronic bands have been proposed to host exotic electronic behavior. Such behavior arises from the quenched kinetic energy of flat band states that promotes interaction between electrons. Such flat bands can also host topologically non-trivial states, allowing for potential platforms for both correlation and topology. However, the extent to which sufficiently flat energy dispersions can be realized in real materials has remained an open question. This project focuses on the synthesis and study of new flat band materials with a focus on new correlated topological phases, Kondo behavior, and connections to spin liquid physics. A key element of this research is a close feedback between targeted material synthesis and advanced spectroscopy to allow for detection and crystal engineering of flat band states. Our efforts will dovetail with research and educational efforts focused on undergraduate efforts to develop novel measurement techniques, creation of visualizations of quantum concepts to improve quantum intuition, and quantum science education/outreach/URM recruitment efforts.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.