Strongly bound excitons dominate electronic relaxation in resonantly excited twisted bilayer graphene
arXiv:1506.00032 · doi:10.1021/acs.nanolett.5b02035
Abstract
When two sheets of graphene stack in a twisted bilayer graphene (tBLG) configuration, the resulting constrained overlap between interplanar 2p orbitals produce angle-tunable electronic absorption resonances. Using a novel combination of multiphoton transient absorption (TA) microscopy and TEM, we resolve the resonant electronic structure, and ensuing electronic relaxation inside single tBLG domains. Strikingly, we find that the transient electronic population in resonantly excited tBLG domains is enhanced many fold, forming a major electronic relaxation bottleneck. 2-photon TA microscopy shows this bottleneck effect originates from a strongly bound, dark exciton state lying 0.37 eV below the 1-photon absorption resonance. This stable coexistence of strongly bound excitons alongside free-electron continuum states has not been previously observed in a metallic, 2D material.
6 pages, 4 figures
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Cited by in corpus (16)
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- Real-space imaging of the tailored plasmons in twisted bilayer graphene
- Observation of Electrically Tunable van Hove Singularities in Twisted Bilayer Graphene from nanoARPES
- Linear response of twisted bilayer graphene: continuum vs. tight-binding models
- Moiré superlattice effects and band structure evolution in near-30-degree twisted bilayer graphene
- Ultrafast photocurrent and absorption microscopy of few-layer TMD devices isolate rate-limiting dynamics driving fast and efficient photoresponse
- High-harmonic spectroscopy of strongly bound excitons in solids
- Magnetic-impurity resonance states for different pairing symmetries in twisted bilayer graphene
- Probing the bright exciton state in twisted bilayer graphene via resonant Raman scattering
- Excitonic effects in twisted bilayer graphene