Excitonic thermalization bottleneck in twisted TMD heterostructures
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arXiv
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| Hauptverfasser: | , , |
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| Format: | Preprint |
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2024
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| _version_ | 1866916115501809664 |
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| author | Meneghini, Giuseppe Brem, Samuel Malic, Ermin |
| author_facet | Meneghini, Giuseppe Brem, Samuel Malic, Ermin |
| contents | Twisted van der Waals heterostructures show an intriguing interface exciton physics including hybridization effects and emergence of moiré potentials. Recent experiments have revealed that moiré-trapped excitons exhibit a remarkable dynamics, where excited states show lifetimes that are several orders of magnitude longer than those in monolayers. The origin of this behaviour is still under debate. Based on a microscopic many-particle approach, we investigate the phonon-driven relaxation cascade of non-equilibrium moiré excitons in the exemplary MoSe$_2$-WSe$_2$ heterostructure. We track the exciton relaxation pathway across different moiré mini-bands and identify the phonon-scattering channels assisting the spatial redistribution of excitons into low-energy pockets of the moiré potential. We unravel a phonon bottleneck in the flat band structure at low twist angles preventing excitons to fully thermalize into the lowest state explaining the measured enhanced emission intensity of excited moiré excitons. Overall, our work provides important insights into exciton relaxation dynamics in flatband exciton materials. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2402_03007 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Excitonic thermalization bottleneck in twisted TMD heterostructures Meneghini, Giuseppe Brem, Samuel Malic, Ermin Mesoscale and Nanoscale Physics Materials Science Twisted van der Waals heterostructures show an intriguing interface exciton physics including hybridization effects and emergence of moiré potentials. Recent experiments have revealed that moiré-trapped excitons exhibit a remarkable dynamics, where excited states show lifetimes that are several orders of magnitude longer than those in monolayers. The origin of this behaviour is still under debate. Based on a microscopic many-particle approach, we investigate the phonon-driven relaxation cascade of non-equilibrium moiré excitons in the exemplary MoSe$_2$-WSe$_2$ heterostructure. We track the exciton relaxation pathway across different moiré mini-bands and identify the phonon-scattering channels assisting the spatial redistribution of excitons into low-energy pockets of the moiré potential. We unravel a phonon bottleneck in the flat band structure at low twist angles preventing excitons to fully thermalize into the lowest state explaining the measured enhanced emission intensity of excited moiré excitons. Overall, our work provides important insights into exciton relaxation dynamics in flatband exciton materials. |
| title | Excitonic thermalization bottleneck in twisted TMD heterostructures |
| topic | Mesoscale and Nanoscale Physics Materials Science |
| url | https://arxiv.org/abs/2402.03007 |