CAREER: Electronic and optical phenomena in moire materials beyond the flat-band paradigm

About This Grant

NONTECHNICAL SUMMARY Imagine materials that look like tiny, patterned quilts at the atomic scale; these are called moiré materials. Their unique structure creates energy conditions (called flat bands) where electrons move slowly and thus interact strongly with one another. In turn, these interactions can lead to surprising phenomena, from new forms of superconductivity to unexpected optical effects with potential for fundamental technological advancements. This project looks beyond the flat-band approaches to explore other unique features of moiré materials, such as their multilayer structure and structural patterns. The research focuses on exploring three main directions: i) Plasmonics in moiré materials. Plasmons are formed by the synchronized motion of electrons that can carry energy at very high speeds, opening possibilities for ultrafast electronics and communication; ii) Interaction of these moiré materials with light, aiming to develop fundamental principles for better solar-cell design and new tools to probe hidden quantum properties of materials; iii) Developing a theory of superconductivity for these moiré systems by comparing superconducting behaviors in different multilayer systems. Alongside the research activity, this project includes an education component designed to broadly improve visibility, accessibility, and participation in the field of condensed matter. The education plan also includes a significant component dedicated to addressing stuttering in academia, aimed at increasing student participation and educational attainment levels. The main initiatives of the plan are: i) to develop a series of do-at-home experiments emphasizing condensed matter principles, ii) to develop a series of undergraduate-friendly events at the National High Magnetic Field Laboratory that will demonstrate the breadth of condensed matter research and help stimulate undergraduate student participation in research, and iii) to compile videos and resources that include examples of role models in academia who stutter and techniques for dealing with stuttering. TECHNICAL SUMMARY: A central feature of moiré systems are the flat electronic bands that promote electron-electron correlations. In addition to the flat bands, however, moiré materials possess other characteristics, such as the multilayer structure or the presence of a superlattice, with implications that go beyond flat-band formation. The project’s overarching intellectual goal is to outline a path to transforming the understanding of moiré materials beyond the conventional paradigm of flat bands promoting interaction effects. The research plan is organized into three thrusts: i) Plasmonics and electron response under high electric fields in moiré materials, which will focus on the exploration of moiré plasmonics, with emphasis on the role of superlattices and correlated effects; introduce a theoretical framework to describe plasmon bands; and propose a new scheme for launching 2D plasmons. ii) Nonlinear optical phenomena in moiré materials: This thrust will develop design principles to optimize photovoltaic response and provide theoretical foundations for demonstrating how optical probes can directly probe quantum textures of many-body states. iii) Multilayer moiré graphene as an analog of the “isotope effect”: One of the key outstanding questions in the moiré graphene field is the nature of the pairing mechanism. The PI will study alternating twisted multilayer graphene systems as a function of layer number to identify the pairing mechanism and formulate testable predictions for future experiments. Alongside the research activity, this project includes an education component designed to broadly improve visibility, accessibility, and participation in the field of condensed matter. The education plan also includes a significant component dedicated to addressing stuttering in academia, aimed at increasing student participation and educational attainment levels. The main initiatives of the plan are: i) to develop a series of do-at-home experiments emphasizing condensed matter principles, ii) to develop a series of undergraduate-friendly events at the National High Magnetic Field Laboratory that will demonstrate the breadth of condensed matter research and help stimulate undergraduate student participation in research, and iii) to compile videos and resources that include examples of role models in academia who stutter and techniques for dealing with stuttering. 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.