Intervalley biexcitons and many-body effects in monolayer MoS[subscript 2]
Author(s)
Frenzel, Alex J.; Lee, Yi-Hsien; Kong, Jing; Gedik, Nuh; Sie, Edbert Jarvis
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Interactions between two excitons can result in the formation of bound quasiparticles, known as biexcitons. Their properties are determined by the constituent excitons, with orbital and spin states resembling those of atoms. Monolayer transition metal dichalcogenides (TMDs) present a unique system where excitons acquire a new degree of freedom, the valley pseudospin, from which a novel intervalley biexciton can be created. These biexcitons comprise two excitons from different valleys, which are distinct from biexcitons in conventional semiconductors and have no direct analog in atomic and molecular systems. However, their valley properties are not accessible to traditional transport and optical measurements. Here, we report the observation of intervalley biexcitons in the monolayer TMD MoS[subscript 2] using ultrafast pump-probe spectroscopy. By applying broadband probe pulses with different helicities, we identify two species of intervalley biexcitons with large binding energies of 60 and 40 meV. In addition, we also reveal effects beyond biexcitonic pairwise interactions in which the exciton energy redshifts at increasing exciton densities, indicating the presence of many-body interactions among them.
Date issued
2015-09Department
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science; Massachusetts Institute of Technology. Department of PhysicsJournal
Physical Review B
Publisher
American Physical Society
Citation
Sie, Edbert J., Alex J. Frenzel, Yi-Hsien Lee, Jing Kong, and Nuh Gedik. "Intervalley biexcitons and many-body effects in monolayer MoS[subscript 2]." Phys. Rev. B 92, 125417 (September 2015). © 2015 American Physical Society
Version: Final published version
ISSN
1098-0121
1550-235X