Journal
NATURE PHYSICS
Volume 15, Issue 3, Pages 228-+Publisher
NATURE RESEARCH
DOI: 10.1038/s41567-018-0362-y
Keywords
-
Categories
Funding
- National Science Foundation [CHE-1362830, DMR-1508412, EFMA-1542741]
- National Science Foundation Graduate Research Fellowship [DGE-1106400]
- US Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division [DE-AC02-05CH11231]
- Ministry of Science and Technology [MoST-106-2119-M-007-023-MY3, MoST-105-2112-M-007-032-MY3]
- Frontier Research Center on Fundamental and Applied Sciences of Matters
- Center for Quantum Technology of National Tsing Hua University
Ask authors/readers for more resources
Monolayer transition metal dichalcogenides (TMDCs) are promising two-dimensional (2D) semiconductors for application in optoelectronics. Their optical properties are dominated by two series of photo-excited exciton states-A (XA) and B (XB)(1,2)-that are derived from direct interband transitions near the band extrema. These exciton states have large binding energies and strong optical absorption(3-6), and form an ideal system to investigate many-body effects in low dimensions. Because spin-orbit coupling causes a large splitting between bands of opposite spins, XA and XB are usually treated as spin-polarized Ising excitons, each arising from interactions within a specific set of states induced by interband transitions between pairs of either spin-up or spin-down bands (TA or TB). Here, by using monolayer MoS2 as a proto-typical system and solving the first-principles Bethe-Salpeter equations, we demonstrate a strong intravalley exchange interaction between TA and TB, indicating that XA and XB are mixed states instead of pure Ising excitons. Using 2D electronic spectroscopy, we observe that an optical excitation of the lower-energy TA induces a population of the higher-energy TB, manifesting the intravalley exchange interaction. This work elucidates the dynamics of exciton formation in monolayer TMDCs, and sheds light on many-body effects in 2D materials.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available