Observation of ultralong valley lifetime in WSe2/MoS2 heterostructures
SCIE
SCOPUS
- Title
- Observation of ultralong valley lifetime in WSe2/MoS2 heterostructures
- Authors
- Kim, Jonghwan; Jin, Chenhao; Chen, Bin; Cai, Hui; Zhao, Tao; Lee, Puiyee; Kahn, Salman; Watanabe, Kenji; Taniguchi, Takashi; Tongay, Sefaattin; Crommie, Michael F.; Wang, Feng
- Date Issued
- 2017-07
- Publisher
- American Association for the Advancement of Science
- Abstract
- The valley degree of freedom in two-dimensional (2D) crystals recently emerged as a novel information carrier in addition to spin and charge. The intrinsic valley lifetime in 2D transition metal dichalcogenides (TMD) is expected to be markedly long due to the unique spin-valley locking behavior, where the intervalley scattering of the electron simultaneously requires a large momentum transfer to the opposite valley and a flip of the electron spin. However, the experimentally observed valley lifetime in 2D TMDs has been limited to tens of nanoseconds thus far. We report efficient generation of microsecond-long-lived valley polarization in WSe2/MoS2 heterostructures by exploiting the ultrafast charge transfer processes in the heterostructure that efficiently creates resident holes in the WSe2 layer. These valley-polarized holes exhibit near-unity valley polarization and ultralong valley lifetime: We observe a valley-polarized hole population lifetime of more than 1 ms and a valley depolarization lifetime (that is, intervalley scattering lifetime) of more than 40 mu s at 10 K. The near-perfect generation of valley-polarized holes in TMD heterostructures, combined with ultralong valley lifetime, which is orders of magnitude longer than previous results, opens up new opportunities for novel valleytronics and spintronics applications.
- URI
- https://oasis.postech.ac.kr/handle/2014.oak/50611
- DOI
- 10.1126/sciadv.1700518
- ISSN
- 2375-2548
- Article Type
- Article
- Citation
- Science advances, vol. 3, no. 7, 2017-07
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