NSF-BSF: Localization and Delocalization in Flat Band Electronic Materials

Non-Technical Abstract: Electronic materials are core to modern technology. As such, new electronic materials and new electronic phenomena can yield a pathway to new technologies. This research focuses on electronic quantum materials that due to their structure and composition host electrons with dynamics that stand between two natural paradigms for electrons in solids- between having localized and itinerant behavior. New insights gained in the synthesis and study in this research has relevance for improving the fundamental understanding of what new states of electronic matter are possible in solids. This in turn offers pathways to further new correlated and quantum information-relevant materials. These research efforts will also improve the broad understanding of the fundamental science of metals, provide enhanced communication within the scientific community and to the public, and provide leading educational opportunities at the boundaries of physics, chemistry, and materials science. Technical Abstract: Materials hosting flat electronic bands have recently emerged as a paradigm that may realize correlated quantum states. A key question in these materials is the fate of the weakly dispersing states when interaction effects become important- in particular the degree to which the electronic states are localized or itinerant. Here, the research team undertakes research in which we comprehensively evaluate flat band states in this context through both material discovery/exploration and targeted characterization experiments. Utilizing thermodynamic and transport probes in addition to x-ray and scanning tunneling microscopy, the research team identifies and characterizes the strength and kind of correlations in a complementary set of flat band materials. It combines material synthesis with advanced spectroscopy, scattering, and theoretical/computational modeling. This approach includes structural characterization, advanced transport, and further aided by collaborative efforts with photoemission and scanning tunneling spectroscopy and theoretical support ranging from topological band theory to ab-initio calculations. This is an approach targeted to ask and answer specific questions about the fate of weakly dispersing states in terms of the localization of their electronic wavefunction and has potential relevance to realize ground-breaking quantum materials for correlation and quantum information-relevant materials. This project has a range of broader impacts. The first is benefit to society through advancements in fundamental understanding of correlated metallic materials with potential applications in e.g., unconventional superconductivity and computationally relevant materials. The next is an enhanced effectiveness of communication with other scientists and the public through improved public outreach efforts. Furthermore, these efforts enable the excitement of materials research to reach broader audiences and interactive demonstrations at the elementary/middle/high school levels. Finally, this enhances USA competitiveness in science and technology through advancements in expertise on correlated condensed matter materials. 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. NSF Award ID: 2618738 | Program: 01002627DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: Joseph Checkelsky | Institution: Massachusetts Institute of Technology, CAMBRIDGE, MA | Award Amount: $619,200 View on NSF Award Search: https://www.nsf.gov/awardsearch/show-award/?AWD_ID=2618738 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2618738.html