A COMPUTATIONAL APPROACH TO COMPLEX JUNCTIONS AND INTERFACES

Two-dimensional (2D) crystals, systems that have strong interactions in two lateral dimensions and relatively weak interactions in the third one, have stimulated tremendous research activity in recent years. With various theoretical methods based on quantum and classical models, this project investigates electronic and magnetic states, and electron and spin transport through 2D tunneling junctions. These are fundamental problems underlying tunneling field-effect transistors that hold promise in future low heat dissipation technology for microelectronics. In recent years, we have studied a number of such systems including metal-phthalocyanines, topological insulators, transition-metal dichalcogenides, graphene, and h-boron nitride.Our research aims to understand the fundamental physics underlying properties and processes at interfaces between two different materials in junctions. Physics in 2D systems has long been a subject of interest. New problems that arise in 2D junctions, including electronic structure, magnetic couplings, the spin helix of topological insulator surfaces states, interface states, and electron and spin transport, are fascinating and challenging. In the presence of electric fields, new states emerge. Field effects and many-body effects are important questions to address, since they can have significant impact on physical properties and processes at a fundamental level. Modern developments in computational power enable us to investigate at a level that goes beyond simple models. Our investigations are based on quantum mechanical principles with high-level theoretical and computational treatments. Finally, we develop advanced transport and density functional theory software codes to further extend modeling and simulation. Our results will have impact on next generation electronic materials and electronics.