Optical-phonon resonances with saddle-point excitons in twisted-bilayer graphene

Abstract

Twisted-bilayer graphene (tBLG) exhibits van Hove singularities in the density of states that can be tuned by changing the twisting angle $\theta$. A $\theta$-defined tBLG has been produced and characterized with optical reflectivity and resonance Raman scattering. The $\theta$-engineered optical response is shown to be consistent with persistent saddle-point excitons. Separate resonances with Stokes and anti-Stokes Raman scattering components can be achieved due to the sharpness of the two-dimensional saddle-point excitons, similar to what has been previously observed for one-dimensional carbon nanotubes. The excitation power dependence for the Stokes and anti-Stokes emissions indicate that the two processes are correlated and that they share the same phonon.

arXiv comment5 pages, 6 figures

References in corpus (11)

• Observation of Van Hove singularities in twisted graphene layers
• Flat Bands in Slightly Twisted Bilayer Graphene
• Kohn Anomalies and Electron-Phonon Interaction in Graphite
• Raman spectroscopy study of rotated double-layer graphene: Misorientation-angle dependence of electronic structure
• Commensuration and Interlayer Coherence in Twisted Bilayer Graphene
• Seeing many-body effects in single- and few-layer graphene: Observation of two-dimensional saddle-point excitons
• Transport properties of graphene in the high-current limit
• Van Hove Singularities and Excitonic Effects in the Optical Conductivity of Twisted Bilayer Graphene
• G band Raman double resonance in twisted bilayer graphene: an evidence of band splitting and folding
• Raman-scattering study of the phonon dispersion in twisted bi-layer graphene
• A non-dispersive Raman D-band activated by well-ordered interlayer interactions in rotationally stacked bi-layer Graphene

Cited by in corpus (14)

• θ-Tunable Photoluminescence from Interlayer Excitons in Twisted Bilayer Graphene
• Strongly bound excitons dominate electronic relaxation in resonantly excited twisted bilayer graphene
• Power dependence of Klyshko's Stokes-anti-Stokes correlation in the inelastic scattering of light
• Observation of Electrically Tunable van Hove Singularities in Twisted Bilayer Graphene from nanoARPES
• Preparation and decay of a single quantum of vibration at ambient conditions
• Flat-band optical phonons in twisted bilayer graphene
• Lifetime and Polarization for Real and Virtual Correlated Stokes-anti-Stokes Raman Scattering in Diamond
• Stokes-anti-Stokes correlated photon properties akin to photonic Cooper pairs
• Ideal pairing of the Stokes and anti-Stokes photons in the Raman process
• Stokes--anti-Stokes light scattering process: -- A photon-wave-function approach
• Effective Hamiltonian for Stokes--anti-Stokes pair generation with pump and probe polarized modes
• Excitonic effects in twisted bilayer graphene
• Emergent broadband polarization entanglement from electronic and phononic Stokes-anti-Stokes indistinguishability
• Exciton lasing in carbon nanotubes below the population inversion threshold via phonon-mediated stimulated emission