Controlling Valley and Spin-Orbit Coupling in Graphene and Bilayer Graphene Nanostructures

点击翻译按钮获取中文摘要

Non-Technical AbstractThis project aims to explore the physics and applications of graphene and bilayer graphene, which consists of one or two layers of carbon atoms arranged in a hexagonal lattice. The arrangement of the carbon atoms leads to unique electronic properties that may become the foundation of a new generation of low-power nanoelectronics and novel types of electronics. These new devices would utilize the electron spin, a quantum mechanical property of electrons, rather than the electron charge, as in conventional electronics. The research activities will prepare graduate students and undergraduate students with advanced technical, methodological and communication skills to contribute to the advancement of nanoscience and nanotechnology in academic or industrial settings. The research team interacts with high-school students (grade 10-12) through a 3-hour workshop combining lecture, demonstration, lab tour and hands-on activities to introduce the properties and applications of atomically thin materials. The workshop is offered to participants through partnership with the Penn State Science U Leadership Summer Camp and the Upward Bound (UB) and Upward Bound Migrant (UBM) programs, which specially target students from low-achieving PA school districts. Technical AbstractSpin, valley, layer and their intimate couplings are distinguishing characteristics of hexagonal 2D crystals, the exploitation of which can lead to new fundamental insights as well as potential applications. The research activities include two thrusts that aim to control the valley degree of freedom in bilayer graphene nanostructures and engineer local spin-orbit coupling in graphene respectively. The first thrust employs dual split-gated devices to study the exotic properties of a new 1D edge mode (kink state) arising at the line junction of two oppositely biased bilayer graphene. Studies of the kink state in the presence of a magnetic field and superconducting electrodes illuminate its interplay with quantum Hall magnetism and proximal superconductivity. The second thrust utilizes adatom functionalization, in particular fluorination, to engineer local spin-orbit coupling in graphene and investigates its impact on spin transport and spin Hall current generation. The research activities combine precision nanolithography, assembly of high-quality 2D material stacks, and low-temperature transport, magneto-transport and spin transport measurements.