Suppression of intervalley exchange coupling in the presence of momentum-dark states in transition metal dichalcogenides
Monolayers of transition metal dichalcogenides (TMDCs) are promising materials for valleytronic applications, since they possess two individually addressable excitonic transitions at the nonequivalent K and K^{′} points with different spins, selectively excitable with light of opposite circular pola...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
American Physical Society
2020-06-01
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| Series: | Physical Review Research |
| Online Access: | http://doi.org/10.1103/PhysRevResearch.2.023322 |
| _version_ | 1827286125767557120 |
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| author | Malte Selig Florian Katsch Samuel Brem Garnik F. Mkrtchian Ermin Malic Andreas Knorr |
| author_facet | Malte Selig Florian Katsch Samuel Brem Garnik F. Mkrtchian Ermin Malic Andreas Knorr |
| author_sort | Malte Selig |
| collection | DOAJ |
| description | Monolayers of transition metal dichalcogenides (TMDCs) are promising materials for valleytronic applications, since they possess two individually addressable excitonic transitions at the nonequivalent K and K^{′} points with different spins, selectively excitable with light of opposite circular polarization. Here, it is of crucial importance to understand the elementary processes determining the lifetime of optically injected valley excitons. In this study, we perform microscopic calculations based on a Heisenberg equation of motion formalism to investigate the efficiency of the intervalley coupling in the presence (W-based TMDCs) and absence (Mo-based TMDCs) of energetically low-lying momentum-dark exciton states after pulsed excitation. While we predict a spin polarization lifetime on the order of some hundreds of femtoseconds in the absence of low-lying momentum-dark states, we demonstrate a strong elongation of the spin-polarization lifetime in the presence of such states due to a suppression of the intervalley exchange coupling. |
| first_indexed | 2024-04-24T10:26:09Z |
| format | Article |
| id | doaj.art-9ee6d84e81d04711b8bbf52d051b6e6f |
| institution | Directory Open Access Journal |
| issn | 2643-1564 |
| language | English |
| last_indexed | 2024-04-24T10:26:09Z |
| publishDate | 2020-06-01 |
| publisher | American Physical Society |
| record_format | Article |
| series | Physical Review Research |
| spelling | doaj.art-9ee6d84e81d04711b8bbf52d051b6e6f2024-04-12T16:55:31ZengAmerican Physical SocietyPhysical Review Research2643-15642020-06-012202332210.1103/PhysRevResearch.2.023322Suppression of intervalley exchange coupling in the presence of momentum-dark states in transition metal dichalcogenidesMalte SeligFlorian KatschSamuel BremGarnik F. MkrtchianErmin MalicAndreas KnorrMonolayers of transition metal dichalcogenides (TMDCs) are promising materials for valleytronic applications, since they possess two individually addressable excitonic transitions at the nonequivalent K and K^{′} points with different spins, selectively excitable with light of opposite circular polarization. Here, it is of crucial importance to understand the elementary processes determining the lifetime of optically injected valley excitons. In this study, we perform microscopic calculations based on a Heisenberg equation of motion formalism to investigate the efficiency of the intervalley coupling in the presence (W-based TMDCs) and absence (Mo-based TMDCs) of energetically low-lying momentum-dark exciton states after pulsed excitation. While we predict a spin polarization lifetime on the order of some hundreds of femtoseconds in the absence of low-lying momentum-dark states, we demonstrate a strong elongation of the spin-polarization lifetime in the presence of such states due to a suppression of the intervalley exchange coupling.http://doi.org/10.1103/PhysRevResearch.2.023322 |
| spellingShingle | Malte Selig Florian Katsch Samuel Brem Garnik F. Mkrtchian Ermin Malic Andreas Knorr Suppression of intervalley exchange coupling in the presence of momentum-dark states in transition metal dichalcogenides Physical Review Research |
| title | Suppression of intervalley exchange coupling in the presence of momentum-dark states in transition metal dichalcogenides |
| title_full | Suppression of intervalley exchange coupling in the presence of momentum-dark states in transition metal dichalcogenides |
| title_fullStr | Suppression of intervalley exchange coupling in the presence of momentum-dark states in transition metal dichalcogenides |
| title_full_unstemmed | Suppression of intervalley exchange coupling in the presence of momentum-dark states in transition metal dichalcogenides |
| title_short | Suppression of intervalley exchange coupling in the presence of momentum-dark states in transition metal dichalcogenides |
| title_sort | suppression of intervalley exchange coupling in the presence of momentum dark states in transition metal dichalcogenides |
| url | http://doi.org/10.1103/PhysRevResearch.2.023322 |
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