Formation of moiré interlayer excitons in space and time

Schmitt, David R.; Bange, Jan Philipp; Bennecke, Wiebke; AlMutairi, AbdulAziz; Meneghini, Giuseppe; Watanabe, Kenji; Taniguchi, Takashi; Steil, Daniel; Lüke, D.; Weitz, R. Thomas; Steil, Sabine; Jansen, G. S. Matthijs; Brem, Samuel; Malić, Ermin; Hofmann, Stephan; Reutzel, Marcel; Mathias, Stefan

doi:10.1038/s41586-022-04977-7

Cited by 80 publications

(108 citation statements)

References 57 publications

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“…A recent TR-MM experiment on the WSe 2 /MoS 2 heterobilayer revealed efficient electron scattering from K to Q points within 50 fs, and form interlayer excitons on a similar timescale. 135 These results provide direct evidence of the charge scattering mechanism during the formation and relaxation of interlayer excitons, with clear resolution of charge carrier distributions at different momenta.…”

Section: Bilayer Dynamicsmentioning

confidence: 64%

“…The energy–momentum fingerprints of the moiré interlayer excitons within the mini Brillouin zone have also been recently captured, in a TR-MM experiment of a twisted WSe 2 /MoS 2 heterostructure. 135 The results revealed interlayer excitons with a Bohr radius of ∼1 nm, trapped in a 2 nm moiré cell. It provided a direct experimental measurement on how the exciton wavefunction can be modulated within the moiré potential.…”

Section: Bilayer Dynamicsmentioning

confidence: 91%

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Time- and angle-resolved photoemission spectroscopy (TR-ARPES) of TMDC monolayers and bilayers

Liu

2023

Chem. Sci.

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Section: Bilayer Dynamicsmentioning

confidence: 64%

Section: Bilayer Dynamicsmentioning

confidence: 91%

Time- and angle-resolved photoemission spectroscopy (TR-ARPES) of TMDC monolayers and bilayers

Liu

2023

Chem. Sci.

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“…Stacking TMD monolayers into van der Waals heterostructures introduces spatially separated interlayer states adding another exciton species with long lifetimes and an out‐of‐plane dipole moment 5–14 . Recent experiments demonstrated the ultrafast charge transfer in optically excited TMD heterobilayers resulting in a formation of interlayer states on a sub‐picosecond timescale 15–20 . Typically, TMD heterobilayers exhibit a type‐II band alignment 21,22 favoring the tunneling of an electron or hole into the opposite layer.…”

Section: Figurementioning

confidence: 99%

Ultrafast phonon‐driven charge transfer in van der Waals heterostructures

2022

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Van der Waals heterostructures built by vertically stacked transition metal dichalcogenides (TMDs) exhibit a rich energy landscape including interlayer and intervalley excitons. Recent experiments demonstrated an ultrafast charge transfer in TMD heterostructures. However, the nature of the charge transfer process has remained elusive. Based on a microscopic and material-realistic exciton theory, we reveal that phonon-mediated scattering via strongly hybridized intervalley excitons governs the charge transfer process that occurs on a sub-100fs timescale. We track the time-, momentum-, and energy-resolved relaxation dynamics of optically excited excitons and determine the temperature-and stacking-dependent charge transfer time for different TMD bilayers. The provided insights present a major step in microscopic understanding of the technologically important charge transfer process in van der Waals heterostructures.

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“…However, while the combination of a photoelectron detection scheme with a pump–probe experiment, i.e., time-resolved ARPES (trARPES), is conceptionally well-established to monitor ultrafast energy dissipation pathways − and to probe optically induced phase transitions − ,− , and band renormalizations, − the direct experimental quantification of the low-energy nonequilibrium quasiparticle self-energy at the femtosecond time scale is still a formidable task. ,, The reason for this challenge lies in the intrinsic measurement technique: femtosecond light pulses require bandwidths of >100 meV due to the time-bandwidth product; hence, an analysis of many-body band renormalizations in the meV range seems to be hardly feasible. Also, the theoretical framework established in equilibrium generally fails to describe many-body interactions in nonequilibrium, , but complex time-resolved NEQ formalisms have to be developed and applied…”

mentioning

confidence: 99%

Far-from-Equilibrium Electron–Phonon Interactions in Optically Excited Graphene

et al. 2022

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Comprehending far-from-equilibrium many-body interactions is one of the major goals of current ultrafast condensed matter physics research. Here, a particularly interesting but barely understood situation occurs during a strong optical excitation, where the electron and phonon systems can be significantly perturbed and the quasiparticle distributions cannot be described with equilibrium functions. In this work, we use time-and angle-resolved photoelectron spectroscopy to study such far-from-equilibrium many-body interactions for the prototypical material graphene. In accordance with theoretical simulations, we find remarkable transient renormalizations of the quasiparticle self-energy caused by the photoinduced nonequilibrium conditions. These observations can be understood by ultrafast scatterings between nonequilibrium electrons and strongly coupled optical phonons, which signify the crucial role of ultrafast nonequilibrium dynamics on manybody interactions. Our results advance the understanding of many-body physics in extreme conditions, which is important for any endeavor to optically manipulate or create non-equilibrium states of matter.

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Formation of moiré interlayer excitons in space and time

Cited by 80 publications

References 57 publications

Time- and angle-resolved photoemission spectroscopy (TR-ARPES) of TMDC monolayers and bilayers

Time- and angle-resolved photoemission spectroscopy (TR-ARPES) of TMDC monolayers and bilayers

Ultrafast phonon‐driven charge transfer in van der Waals heterostructures

Far-from-Equilibrium Electron–Phonon Interactions in Optically Excited Graphene

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