Phonon-Assisted Intervalley Scattering Determines Ultrafast Exciton Dynamics in MoSe 2 Bilayers
| Autor: | Ermin Malic, Alexander Achstein, Andreas Knorr, Kevin Sampson, Sophia Helmrich, Kai Hao, Malte Selig, Xiaoqin Li, Di Huang, Kha Tran, Ulrike Woggon, Carter Young, Nina Owschimikow |
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| Rok vydání: | 2021 |
| Předmět: |
Physics
Condensed Matter - Materials Science education.field_of_study Quantum decoherence Condensed Matter - Mesoscale and Nanoscale Physics Condensed matter physics Phonon Scattering Quantum dynamics Bilayer Exciton Relaxation (NMR) Population Materials Science (cond-mat.mtrl-sci) FOS: Physical sciences General Physics and Astronomy 02 engineering and technology Condensed Matter::Mesoscopic Systems and Quantum Hall Effect 021001 nanoscience & nanotechnology 01 natural sciences Mesoscale and Nanoscale Physics (cond-mat.mes-hall) 0103 physical sciences 010306 general physics 0210 nano-technology education |
| Zdroj: | Physical Review Letters |
| ISSN: | 0031-9007 0027-1349 |
| DOI: | 10.1103/physrevlett.127.157403 |
| Popis: | While valleys (energy extrema) are present in all band structures of solids, their preeminent role in determining exciton resonances and dynamics in atomically thin transition metal dichalcogenides (TMDC) is unique. Using two-dimensional coherent electronic spectroscopy, we find that exciton decoherence occurs on a much faster time scale in MoSe$_2$ bilayers than that in the monolayers. We further identify two population relaxation channels in the bilayer, a coherent and an incoherent one. Our microscopic model reveals that phonon-emission processes facilitate scattering events from the $K$ valley to other lower energy $\Gamma$ and $\Lambda$ valleys in the bilayer. Our combined experimental and theoretical studies unequivocally establish different microscopic mechanisms that determine exciton quantum dynamics in TMDC monolayers and bilayers. Understanding exciton quantum dynamics provides critical guidance to manipulation of spin/valley degrees of freedom in TMDC bilayers. Comment: 6 pages, 4 figures |
| Databáze: | OpenAIRE |
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