CDS&E: Excited-state properties and the impact of random defects in quantum materials

Lehigh University, Bethlehem PA

Investigators

Abstract

NONTECHNICAL SUMMARY This award supports theoretical and computational research and education on techniques that will enhance and expand our current scientific knowledge of the properties of realistic two-dimensional (2D) materials, which consist of a single layer of atoms. Just as the discovery of semiconductors revolutionized computation and information storage, functional 2D materials and materials formed by vertically stacking 2D materials have the potential to revolutionize every aspect of our lives. They are actively being explored for both fundamental research and modern device applications, including efficient generation, storing, and transporting power across the national grid with minimal losses, ultrasensitive sensors capable of synchronous monitoring, and efficient disease detection and diagnosis. Critical to actualizing these novel and transformative technological applications is a fundamental understanding of the interplay between the exotic phases that abound in 2D materials. Due to the complexity of electron-electron interactions coupled with materials' inhomogeneities, standard computational modeling approaches suitable for perfect bulk materials often become unreliable for modeling 2D materials. The PI and his team will develop and employ advanced theoretical and computational techniques that will account for strong electron-electron interaction and inhomogeneous nature of 2D materials to explore physical properties and phenomena that could potentially be harnessed for technological advances. This award also supports various education and outreach activities. The PI will (1) train both undergraduate and graduate students in computational physics, data science, and materials science research, (2) deliver corresponding interdisciplinary hands-on materials modeling courses by integrating research with teaching, and (3) perform educational outreach with the potential to enhance science education and increased public scientific awareness and literacy within the Lehigh Valley. TECHNICAL SUMMARY This award supports theoretical and computational research and education on techniques that will enhance and expand our current scientific knowledge of the properties of two-dimensional (2D) materials beyond idealistic models of perfectly ordered or structurally averaged materials. To tackle the challenges of studying moderately correlated realistic 2D materials, the PI will develop and employ advanced numerical and theoretical techniques accounting for Coulomb interactions, random disorder, complete orbital structure, and the presence of dielectric screening within the material. Several open questions that have come into focus due to recent experimental discoveries in 2D-based quantum materials will be addressed, such as (1) What is the physical nature of the nanoscale phase coexistence between material’s imperfection, spatial correlations, and Coulomb interactions? (2) What is the fate of Coulomb and exciton interactions, and quantum criticality near broken symmetry states in the presence of material imperfection? (3) Can the defect-induced broken symmetry state, e.g., Mott physics and metal-insulator quantum transition be harnessed through band-engineering? The PI will exploit the potential to realize defect-induced transitions between the various broken-symmetry states. This award also supports various education and outreach activities. The PI will (1) train both undergraduate and graduate students in computational physics, data science, and materials science research, (2) deliver corresponding interdisciplinary hands-on materials modeling courses by integrating research with teaching, and (3) perform educational outreach with the potential to enhance STEM education and increased public scientific awareness and literacy within the Lehigh Valley. 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.