Strong-Coupling Phenomena at the Metal-Insulator Transition

Florida State University, Tallahassee FL

Investigators

Abstract

NON-TECHNICAL SUMMARY Modern technology often requires fine-tuning of electronic properties of conductors close to the insulating state–-the metal-insulator transition region. Experimental progress in the last few years have made this regime accessible, with the discovery of new quantum materials and devices, producing a veritable avalanche of yet-unexplained experimental data. In the next three years, the PI will develop novel theoretical approaches that will provide the necessary tools to understand these phenomena, which are being realized in systems ranging from molecular organic materials to various devices made from stacking two-dimensional sheets of materials. Here, the electron-electron interactions in presence of materials disorder dramatically modify the energy landscape in which the electrons travel, sometimes disrupting their ability to move within the conductor. The ability to theoretically describe such situations will open new avenues for the design of novel experimental platforms with specific properties required by modern quantum science and engineering. This project will allow training of graduate students in theoretical and computational condensed matter physics. The PI will continue to promote and enhance scientific and technological understanding and importance of our research to the general public through various outreach activities: 1) Presentation of lectures at local schools and acting as a judge at regional science fairs; 2) Participating in the Florida State University Physics Department Open House activities and the National High Magnetic Field Laboratory annual Open House activities. The PI has been invited to act as, and will assume the role of, faculty advisor of a grass-roots undergraduate student organization named "The Future Physicist Society at FSU". This will provide an effective avenue to assist the students in taking the next career step after leaving FSU. TECHNICAL SUMMARY In the following three years, the PI will theoretically examine several fundamental aspects of the metal-insulator transition (MIT) on several new experimental platforms, including Mott organic systems, various moiré bilayers devices, as well as two-dimensional quantum meta-materials based on ion implantation in semiconductors. Here, several distinct MIT regimes will be examined and theoretically described, where different physical mechanisms dominate, as follows: A) A theory of disorder-dominated MITs (away from the Mott regime) will be developed, focusing on the polaronic picture based on a self-consistent (saddle-point) but nonpeturbative approach, allowing, however, systematic corrections, which will also be included; B) Disorder effects will also be examined in the Mott (interaction-dominated), as well as in the related heavy-fermion regimes. Several of these regimes can be accessed and identified experimentally in the same moiré devices, allowing comparative studies and promising a new conceptual understanding of the MIT transition region. This project will allow training of graduate students in theoretical and computational condensed matter physics. The PI will continue to promote and enhance scientific and technological understanding and importance of our research to the general public through various outreach activities: 1) Presentation of lectures at local schools and acting as a judge at regional science fairs; 2) Participating in the Florida State University Physics Department Open House activities and the National High Magnetic Field Laboratory annual Open House activities. The PI has been invited to act as, and will assume the role of, faculty advisor of a grass-roots undergraduate student organization named "The Future Physicist Society at FSU". This will provide an effective avenue to assist the students in taking the next career step after leaving FSU. 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.