Observation of ~100% valley-coherent excitons in monolayer MoS2 through giant enhancement of valley coherence time
Abstract In monolayer transition metal dichalcogenide semiconductors, valley coherence degrades rapidly due to a combination of fast scattering and inter-valley exchange interaction. This leads to a sub-picosecond valley coherence time, making coherent manipulation of exciton a highly challenging ta...
| Glavni autori: | , , , |
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| Format: | Članak |
| Jezik: | English |
| Izdano: |
Nature Publishing Group
2023-07-01
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| Serija: | Light: Science & Applications |
| Online pristup: | https://doi.org/10.1038/s41377-023-01220-4 |
| _version_ | 1827899614312792064 |
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| author | Garima Gupta Kenji Watanabe Takashi Taniguchi Kausik Majumdar |
| author_facet | Garima Gupta Kenji Watanabe Takashi Taniguchi Kausik Majumdar |
| author_sort | Garima Gupta |
| collection | DOAJ |
| description | Abstract In monolayer transition metal dichalcogenide semiconductors, valley coherence degrades rapidly due to a combination of fast scattering and inter-valley exchange interaction. This leads to a sub-picosecond valley coherence time, making coherent manipulation of exciton a highly challenging task. Using monolayer MoS2 sandwiched between top and bottom graphene, here we demonstrate fully valley-coherent excitons by observing ~100% degree of linear polarization in steady state photoluminescence. This is achieved in this unique design through a combined effect of (a) suppression in exchange interaction due to enhanced dielectric screening, (b) reduction in exciton lifetime due to a fast inter-layer transfer to graphene, and (c) operating in the motional narrowing regime. We disentangle the role of the key parameters affecting valley coherence by using a combination of calculation (solutions of Bethe-Salpeter and Maialle-Silva-Sham equations) and a careful choice of design of experiments using four different stacks with systematic variation of screening and exciton lifetime. To the best of our knowledge, this is the first report in which the excitons are found to be valley coherent in the entire lifetime in monolayer semiconductors, allowing optical readout of valley coherence possible. |
| first_indexed | 2024-03-12T23:20:18Z |
| format | Article |
| id | doaj.art-62e9a0b463444152b16a17ce0b568d82 |
| institution | Directory Open Access Journal |
| issn | 2047-7538 |
| language | English |
| last_indexed | 2024-03-12T23:20:18Z |
| publishDate | 2023-07-01 |
| publisher | Nature Publishing Group |
| record_format | Article |
| series | Light: Science & Applications |
| spelling | doaj.art-62e9a0b463444152b16a17ce0b568d822023-07-16T11:28:24ZengNature Publishing GroupLight: Science & Applications2047-75382023-07-011211710.1038/s41377-023-01220-4Observation of ~100% valley-coherent excitons in monolayer MoS2 through giant enhancement of valley coherence timeGarima Gupta0Kenji Watanabe1Takashi Taniguchi2Kausik Majumdar3Department of Electrical Communication Engineering, Indian Institute of ScienceResearch Center for Functional Materials, National Institute for Materials ScienceInternational Center for Materials Nanoarchitectonics, National Institute for Materials ScienceDepartment of Electrical Communication Engineering, Indian Institute of ScienceAbstract In monolayer transition metal dichalcogenide semiconductors, valley coherence degrades rapidly due to a combination of fast scattering and inter-valley exchange interaction. This leads to a sub-picosecond valley coherence time, making coherent manipulation of exciton a highly challenging task. Using monolayer MoS2 sandwiched between top and bottom graphene, here we demonstrate fully valley-coherent excitons by observing ~100% degree of linear polarization in steady state photoluminescence. This is achieved in this unique design through a combined effect of (a) suppression in exchange interaction due to enhanced dielectric screening, (b) reduction in exciton lifetime due to a fast inter-layer transfer to graphene, and (c) operating in the motional narrowing regime. We disentangle the role of the key parameters affecting valley coherence by using a combination of calculation (solutions of Bethe-Salpeter and Maialle-Silva-Sham equations) and a careful choice of design of experiments using four different stacks with systematic variation of screening and exciton lifetime. To the best of our knowledge, this is the first report in which the excitons are found to be valley coherent in the entire lifetime in monolayer semiconductors, allowing optical readout of valley coherence possible.https://doi.org/10.1038/s41377-023-01220-4 |
| spellingShingle | Garima Gupta Kenji Watanabe Takashi Taniguchi Kausik Majumdar Observation of ~100% valley-coherent excitons in monolayer MoS2 through giant enhancement of valley coherence time Light: Science & Applications |
| title | Observation of ~100% valley-coherent excitons in monolayer MoS2 through giant enhancement of valley coherence time |
| title_full | Observation of ~100% valley-coherent excitons in monolayer MoS2 through giant enhancement of valley coherence time |
| title_fullStr | Observation of ~100% valley-coherent excitons in monolayer MoS2 through giant enhancement of valley coherence time |
| title_full_unstemmed | Observation of ~100% valley-coherent excitons in monolayer MoS2 through giant enhancement of valley coherence time |
| title_short | Observation of ~100% valley-coherent excitons in monolayer MoS2 through giant enhancement of valley coherence time |
| title_sort | observation of 100 valley coherent excitons in monolayer mos2 through giant enhancement of valley coherence time |
| url | https://doi.org/10.1038/s41377-023-01220-4 |
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