Probing and Manipulating Novel Electronic States in Graphene Multilayers

Abstract

The pursuit of understanding, manipulating, and engineering quantum materials has opened new avenues for exploring exotic states of matter. Among these materials, graphene multilayers represent a rapidly emerging platform in which the electronic properties can be drastically tuned through artificial control of stacking configurations. These systems provide a unique opportunity to investigate a wide range of correlated and topological phases, including (Quantum) anomalous Hall effects, fractional quantum Hall states, and unconventional superconductivity. Their versatility offers an exciting pathway for advancing both fundamental science and future technologies in quantum information and materials engineering. This dissertation presents a comprehensive study of the electronic transport properties of graphene multilayers and the development of novel experimental techniques to manipulate their quantum states. First, we revisit the transport behavior of monolayer, Bernal bilayer, and twisted bilayer graphene across a range of twist angles, uncovering new and unexpected phenomena. Building on these findings, we introduce two complementary tuning approaches designed for cryogenic transport measurements: the application of high pressure using a diamond anvil cell and the precise control of in-plane uniaxial strain. These techniques open access to previously unexplored regimes, enabling detailed studies of symmetry breaking, electronic correlations, and topological transitions. The insights gained from these measurements deepen our understanding of the ground states in graphene multilayers and demonstrate their potential as a versatile platform for exploring strongly correlated and topological quantum phases.