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The dramatic effect of spin-orbit coupling in correlated graphene

Mathematical Physics Seminar

Speaker: Alex Thomson, UC Davis
Location: 3024 QMAP/PSEL
Start time: Tue, Jun 6 2023, 4:10PM

The discovery of superconductivity in graphene heterostructures has triggered a renewed interest in the field. Key to this development are experimental techniques and system setups designed to quench the kinetic energy of graphene’s electrons, allowing interactions to play a more prominent role and resulting in a vast array of correlated phases. I focus on two broad categories of superconducting graphene systems: magic-angle moiré heterostructures and Bernal bilayer graphene. In the former, graphene sheets are stacked offset by a ‘magic’ twist angle which yields an enlarged moiré unit cell and extremely flat bands at charge neutrality. By contrast, band flattening in Bernal bilayer graphene follows from the in situ application of an out-of-plane electric field. I argue that spin-orbit coupling—largely negligible in hBN-encapsulated graphene—is induced in both systems when they are constructed adjacent to monolayer WSe2. The resulting modifications to the phase diagram provide important information on the correlated phases and nature of superconductivity in these systems and moreover suggest applications to quantum technology.