Formation of moiré interlayer excitons in space and time
Journal article, 2022
Moiré superlattices in atomically thin van der Waals heterostructures hold great promise for extended control of electronic and valleytronic lifetimes1-7, the confinement of excitons in artificial moiré lattices8-13 and the formation of exotic quantum phases14-18. Such moiré-induced emergent phenomena are particularly strong for interlayer excitons, where the hole and the electron are localized in different layers of the heterostructure19,20. To exploit the full potential of correlated moiré and exciton physics, a thorough understanding of the ultrafast interlayer exciton formation process and the real-space wavefunction confinement is indispensable. Here we show that femtosecond photoemission momentum microscopy provides quantitative access to these key properties of the moiré interlayer excitons. First, we elucidate that interlayer excitons are dominantly formed through femtosecond exciton-phonon scattering and subsequent charge transfer at the interlayer-hybridized Σ valleys. Second, we show that interlayer excitons exhibit a momentum fingerprint that is a direct hallmark of the superlattice moiré modification. Third, we reconstruct the wavefunction distribution of the electronic part of the exciton and compare the size with the real-space moiré superlattice. Our work provides direct access to interlayer exciton formation dynamics in space and time and reveals opportunities to study correlated moiré and exciton physics for the future realization of exotic quantum phases of matter.
Author
David Schmitt
University of Göttingen
Jan Philipp Bange
University of Göttingen
Wiebke Bennecke
University of Göttingen
Abdul Aziz AlMutairi
Department of Engineering
Giuseppe Meneghini
Philipps University Marburg
Kenji Watanabe
National Institute for Materials Science (NIMS)
Takashi Taniguchi
National Institute for Materials Science (NIMS)
Daniel Steil
University of Göttingen
D. Russell Luke
University of Göttingen
R. Thomas Weitz
University of Göttingen
Sabine Steil
University of Göttingen
G. S.Matthijs Jansen
University of Göttingen
Samuel Brem
Philipps University Marburg
Ermin Malic
Philipps University Marburg
2D-Tech
Chalmers, Physics, Condensed Matter and Materials Theory
Stephan Hofmann
Department of Engineering
Marcel Reutzel
University of Göttingen
Stefan Mathias
University of Göttingen
Nature
0028-0836 (ISSN) 1476-4687 (eISSN)
Vol. 608 7923 499-503Subject Categories
Atom and Molecular Physics and Optics
Other Physics Topics
Condensed Matter Physics
DOI
10.1038/s41586-022-04977-7
PubMed
35978130