Transport studies of periodically driven electronic systems

Georgia State University Research Foundation, Inc., Atlanta GA

Investigators

Abstract

Non-technical Description: The personal computer, the world wide web, the cell phone, high-definition television, electronic sensors, and the expected autonomous car and artificial intelligence, help drive the growth of the United States gross domestic product and these growth engines rely heavily upon technological advances made in semiconductor electronic materials. Although associated electronic materials are typically utilized in their natural equilibrium steady states in three dimensions, theoretical studies suggest the possibility of realizing new capability when the constituent electrons in these materials are artificially rearranged, such as confining them only to two-dimensions. This research examines the electronic properties of two-dimensional systems subjected to excitation from low energy light sources in search of predicted physical phenomena, with a view towards potential applications. This research is timely because recent advances in atomically layered materials has greatly expanded both the universe of available materials for such studies and scope of observable new phenomena. This research project is carried out at Georgia State University, one of the universities which serves the most diverse population in the nation. It will involve undergraduate and high school students, including those from historically underrepresented groups and women, and translate their abilities into the pursuit of career paths in the STEM field, by providing them early exposure to a supportive, confidence building, research experience. The project will also help to add underrepresented sections of society to the nation’s science and technology skill base for the electronics, photonics, defense, and wireless communications industries. Technical Description: This research experimentally examines the magnetoelectronic response under low energy steady state photoexcitation of semiconductor heterostructures and 2D atomic-layered materials including mono-layer, bilayer, and twisted bilayer graphene, atomically thin hexagonal boron nitride (h-BN), and possibly transition metal-dichalcogenides. Photo-excited transport under steady state low energy photoexcitation is mostly unexplored in the above-mentioned material systems partly because of the experimental difficulties encountered in simultaneously bringing together high magnetic fields, low temperatures, low energy photoexcitation over a wide band, with good quality samples. The research team consisting of graduate students, undergraduates, and high school students, will build up layered semiconductor devices and 2D atomic-layered crystals by applying electron beam lithography, plasma etch, and metallization; and examine the properties of electrically contacted and non-contacted devices in the presence of a magnetic field under microwave, mm-wave, and terahertz photoexcitation. Here, some specific problems of interest include the study, to measure particle characteristics, of radiation-induced magnetoresistance oscillations and associated zero-resistance states, for electrons and composite fermions, in the parabolic GaAs/AlGaAs and bilayer graphene systems, as well as in the linearly dispersed monolayer graphene system. Another aim is to clarify the dependence of the fundamental field for the radiation induced oscillations for both electrons and composite fermions on the Fermi wave vector in monolayer graphene. In the twisted bilayer graphene system, one aim is to study the velocity renormalization versus the twist angle. In other STEM aspects, there will be outreach to local high school science teachers to expose the students to nanoscience via online lectures/seminars and host such high school students for nanoscience-based laboratory investigations at Georgia State University. 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.