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Formation of moiré interlayer excitons in space and time
David Schmitt1, Jan Philipp Bange1, Wiebke Bennecke1
1I. Physikalisches Institut, Georg-August-Universität Göttingen, Göttingen, Germany.
Nature
|August 17, 2022
Summary
Moiré superlattices enable control over electron behavior in van der Waals heterostructures. This study uses advanced microscopy to reveal ultrafast interlayer exciton formation and confinement within these moiré structures.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Optics
Background:
- Atomically thin van der Waals heterostructures with moiré superlattices offer tunable electronic and valleytronic properties.
- Interlayer excitons, with electrons and holes in different layers, are crucial for correlated moiré and exciton physics.
- Understanding ultrafast interlayer exciton formation and wavefunction confinement is key to harnessing moiré phenomena.
Purpose of the Study:
- To quantitatively investigate the ultrafast formation dynamics and real-space wavefunction confinement of interlayer excitons in moiré superlattices.
- To elucidate the mechanisms governing interlayer exciton formation.
- To demonstrate the capability of femtosecond photoemission momentum microscopy in probing moiré exciton properties.
Main Methods:
- Utilizing femtosecond photoemission momentum microscopy to probe interlayer excitons.
- Analyzing exciton formation pathways involving exciton-phonon scattering and charge transfer.
- Reconstructing the real-space wavefunction distribution of the electronic component of excitons.
Main Results:
- Interlayer excitons are primarily formed via femtosecond exciton-phonon scattering and charge transfer at interlayer-hybridized Σ valleys.
- A distinct momentum fingerprint of interlayer excitons directly reflects the moiré superlattice modulation.
- The reconstructed electronic wavefunction size correlates with the moiré superlattice dimensions.
Conclusions:
- Femtosecond photoemission momentum microscopy provides unprecedented spatiotemporal insight into interlayer exciton dynamics.
- The study reveals opportunities for exploring correlated moiré and exciton physics.
- This research paves the way for the realization of novel quantum phases of matter in moiré heterostructures.
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