Coulomb interaction, phonons, and superconductivity in twisted bilayer graphene
Tommaso Cea, F. Guinea
Abstract
The polarizability of twisted bilayer graphene, due to the combined effect of electron-hole pairs, plasmons, and acoustic phonons, is analyzed. The screened Coulomb interaction allows for the formation of Cooper pairs and superconductivity in a significant range of twist angles and fillings. The tendency toward superconductivity is enhanced by the coupling between longitudinal phonons and electron-hole pairs. Scattering processes involving large momentum transfers, Umklapp processes, play a crucial role in the formation of Cooper pairs. The magnitude of the superconducting gap changes among the different pockets of the Fermi surface.
Topics & Concepts
Condensed matter physicsSuperconductivityBilayer graphenePhononCoulombPhysicsGrapheneFermi surfaceFermi energyFermi levelPlasmonMomentum (technical analysis)QuasiparticleQuantum mechanicsFinanceElectronEconomicsGraphene research and applicationsQuantum and electron transport phenomenaPhysics of Superconductivity and Magnetism