CAREER: Developing Graphene Superlattices in a Massive-Massless Hybrid Electron System

West Virginia University Research Corporation, Morgantown WV

Investigators

Abstract

Nontechnical Description: The ability to control the electronic properties of graphene (an atomic layer of carbon) with nanoscale precision is critical for the implementation of graphene-based devices. However, many existing techniques used in traditional semiconductors are much less effective on graphene due to its unique structure. To address this challenge, a fundamental materials study enabling such precision control in graphene is developed in this CAREER award project. Overlapping an artificial periodic electronic structure on top of graphene has been predicted to be an effective approach for such a task. Stemming from a hybrid bilayer system that integrates graphene with complex oxide interfaces, this project focuses on understanding the controlling mechanisms which could lead to an on-demand tuning technique for future innovative graphene-based electronic devices. Taking advantage of the novel technique developed through this research, the project will produce a new class module on "physics in nanoelectronics" with demonstrations and experimental opportunities for students involved. The associated videos and course materials will be shared with the broader education community. Undergraduate students will be involved in both the research project and the development of the class module. In addition the course module and related materials will be adopted by outreach programs tailored for students from underrepresented groups to promote their interest in physics and a future career in science. Technical Description: The research goal of this CAREER award is to develop a method of band engineering in graphene, which will support the design of unconventional superlattice-based graphene electronics, and to study its fundamental mechanism. The study is based on both the hybrid bilayer system integrating graphene with LaAlO3(LAO)/SrTiO3(STO) interfaces and the conducting atomic force microscopy (c-AFM) technique. The nanoscale periodic patterns of a two dimensional electron gas (2DEG) reversibly created at the LAO/STO interface using c-AFM are expected to generate reprogrammable superlattice potentials in graphene for desired band modifications. The interactions between the massive regular fermions confined at the LaAlO3/SrTiO3 interfaces and the massless Dirac fermions in graphene are studied. Controlling the proximity effects in graphene/complex oxide heterostructures is expected to give rise to exciting new physics and novel functionalities. In addition, the close coupling between oxides and a high-mobility graphene layer could be very powerful for probing the properties at the oxide interfaces, such as sub-band structures and electron correlations. These studies may help to shed light on some of the unsolved problems in complex oxides.