Abstract
We report a theoretical study of the many-body effects of electron–electron interaction on the ground-state and spectral properties of double-layer graphene. Using a projector-based renormalization method we show that if a finite-voltage difference is applied between the graphene layers, electron–hole pairs can be formed and—at very low temperatures—an excitonic instability might emerge in a double-layer graphene structure. The single-particle spectral function near the Fermi surface exhibits a prominent quasiparticle peak, different from neutral (undoped) graphene bilayers. Away from the Fermi surface, we find that the charge carriers strongly interact with plasmons, thereby giving rise to a broad plasmaron peak in the angle-resolved photoemission spectrum.
Highlights
In characterizing many-body aspects of Single-layer graphene (SLG), Bilayer graphene (BLG) and double-layer graphene (DLG), and the electron-electron, electron-hole and electron-plasmon interaction effects, the single-particle spectral function A(k, ω) gives detailed information
Using a projector-based renormalization method we show that if a finite voltage difference is applied between the graphene layers electron-hole pairs can be formed and—at very low temperatures—an excitonic instability might emerge in a double-layer graphene structure
Analyzing by means of a projector-based renormalization method Coulomb interaction effects within a generic graphene bilayer model, we suppose that electron-hole pair formation and condensation might appear in a double-layer graphene (DLG) system at least at zero temperature, if charge imbalance between the layers is induced by an external electric field
Summary
In characterizing many-body aspects of SLG, BLG and DLG, and the electron-electron, electron-hole and electron-plasmon interaction effects, the single-particle spectral function A(k, ω) gives detailed information. We employ the projector-based renormalization method (PRM) to determine the ground-state and spectral properties of an effective graphene bilayer model describing the interaction and possibly pairing of electrons from the top bilayer with holes from the bottom layer [cf figure 1 (a)].
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